Revert "CodeGen: annotate ObjC ARC functions with ABI constraints"

This reverts commit a92ce662c187e295059100cd71bf41ed9ea3b88c.

This commit broke the placement of the Obj-C autoreleased return values handshakes, let's revert it while investigating why.

rdar://problem/34577146

Conflicts:
	lib/CodeGen/CGObjC.cpp
2 files changed