lli/RecordingMemoryManager.cpp: Make it complain if _GLOBAL_OFFSET_TABLE_ were not provided.

FIXME: Would it be responsible to provide GOT?
X86TargetMachine.cpp: Clarify to emit GOT in i686-{cygming|win32}-elf for mcjit.

I suppose all "lli -use-mcjit i686-*" should require GOT, (and to fail.)