Bug 927427 - use __LP64__ in FileUtils.cpp for Linux; r=bsmedberg
Bug 927428 - use __LP64__ instead of HAVE_64BIT_OS in the linker; r=glandium
Bug 927535 - interrogate ctypes to find out about win32/win64 bits instead of preprocessor macros; r=bholley
Bug 927551 - make darwin xptcall sources compilable in a singlepass universal build; r=bsmedberg,glandium