memstore: compare the raw pointer to NULL

os/MemStore.cc:259:30: error: use of overloaded operator '!=' is ambiguous (with operand types 'ObjectRef' (aka 'shared_ptr<MemStore::Object>') and 'long')
  return (c->get_object(oid) != __null);
          ~~~~~~~~~~~~~~~~~~ ^  ~~~~~~
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:4787:1: note: candidate function [with _Tp = MemStore::Object]
operator!=(const shared_ptr<_Tp>& __x, nullptr_t) throw()
^
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, long)
  return (c->get_object(oid) != __null);
                             ^
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(int, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long double, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(double, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(long long, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(__int128, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned int, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned long long, unsigned __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, long double)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(float, float)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, __int128)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, unsigned int)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, unsigned long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, unsigned long long)
os/MemStore.cc:259:30: note: built-in candidate operator!=(unsigned __int128, unsigned __int128)
1 error generated.
make[3]: *** [os/MemStore.lo] Error 1

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>