Find a way to not leak ACE/xerces headers/definitions in MapGuide common headers

[jng]

The SWIG bindings do not call anything in ace or xerces, but due to their headers/types leaking out of Foundation/MapGuideCommon, this gives us grief when building the PHP api due to its headers conflicting with ACE on certain platform definitions (eg. uid_t, gid_t, struct dirent). Also the leaking of xerces headers is completely unnecessary

Our current workaround has been to overlay patched PHP headers to resolve such conflicts, but this is not a tenable solution. We should either properly encapsulate or #ifdef any traces of ACE and xerces out of these headers when building SWIG bindings.