Fix "long double" handling and differences between MSFT and GCC compilers. Fix compliance issues with ISO/IEC 9899:199409 New Function declarations: setenv(), fparseln(), GetFileNameFromPath(), rename() git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12060 6f19259b-4bc3-4df7-8a09-765794883524