SERVER-9325 Add blockCheckSupported and hostInfo support to Solaris/SmartOS

Implement a processinfo_*.cpp file for Solaris, providing support for
blockCheckSupported features and the the hostInfo command.  Rewrite the
readLineFromFile() function from processinfo_linux2.cpp and move it into
processinfo.cpp where it can be called for Solaris as well as Linux.
SERVER-7404 Link to posix_fadvise at runtime for Solaris

For the Solaris/SmartOS build, do not make direct calls to posix_fadvise,
which is present in Solaris 11 but not in Solaris 10.  Instead, see if
it is available in a loaded library (which will be libc.so.1) at runtime
and either call it or call an emulation.  The emulation is a no-op.