Fix bug where calls to externally-defined functions were treated as never returning pointers to anything and never leaking their arguments to the external context.
Merge branch 'andersen' into experimental-getmodrefinfo

Conflicts:
	lib/Analysis/Andersen/InstructionAnalyzer.cpp
Fix regression in 45be632dee1c33737ef135c9f0a8cbd96bcc96b3 where externally-defined functions were treated as never modifying or referencing anything (analogous to the problem fixed by 350758f6ad588f1d553a887e4ef67d5bf6c0d9d6).