Making tcmalloc v2.2 the default tcmalloc version (over 1.7).

runtime/etc/Makefile.mem-tcmalloc: Need to link -lpthread on some systems

runtime/src/mem/tcmalloc/Makefile.share: -Werror was catching deprecated
  warnings on OSX, turn off the warnings here.

tcmalloc-interface.cc: In tcmalloc v1.7, an array of various system allocators
  were used when the heap ran out. If one allocator in the array didn't work, 
  then it tried the next one. We had to provide our own ChapelSysAllocator
  for use in multilocale, and had to make sure that it was the only one 
  allowed. This was the reason for adding functions to Register our allocator 
  and disable all others.

  In v2.2, a 'sys_alloc' variable is used instead of an array. We can set 
  this variable with MallocExtension directly, and no other allocators
  will be used.

third-party/tcmalloc/Makefile: --enable-minimal accomplishes the same as the
  --disable-* flags


git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@23593 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
adding future for passing atomic variables by ref

git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@23594 3a8e244f-b0f2-452b-bcba-4c88e055c3ca