Add some compatibility definitions for OpenSolaris source.
Add some compatibility definitions for OpenSolaris source.

These are only defined if _SOLARIS_C_SOURCE is defined, so they don't
polute the FreeBSD compile environment.

They are used all over the OpenSolaris source, so defining them here
removes the need to continually resolve differences in FreeBSD system
haeder files from Solaris header files.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase