Trying to fix the library callback test on non-linux systems
Update API to fix inconsistent linkage warnings
Fix callback test, both in finding *and* executing the test binray
Mac might be working now;
I dont have one to test on, but it seems the code simply wasnt chdir-ing on Macs;
Looking at the docs, it seems Mac has the chdir() function inside unistd just like other *nix;
Thus I just changed the code so Mac and *nix are both in the same #else
Merge remote-tracking branch 'origin/develop' into FixLibraryCallbackTest
Merge pull request #4582 from NREL/FixLibraryCallbackTest

Trying to fix the library callback test on non-linux systems