Update mod_loader to use Posix dl functions rather than deprecated NS functions. Add support for embedded mode on MacOSX as an app bundle as well as the existing framework

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@58367 65644016-39b1-43b1-bf79-96bc8fe82c15
Add support for embedded mode on MacOSX as an app bundle as well as the existing framework

git-svn-id: svn+ssh://svn.code.sf.net/p/firebird/code/firebird/branches/B2_5_Release@58372 65644016-39b1-43b1-bf79-96bc8fe82c15