Teach GlobalISelEmitter to treat used iPTRAny operands as pointer operands

Overloaded intrinsics can use iPTRAny in used/input operands.

The GlobalISelEmitter doesn't know that these are pointers, so it treats them
as scalars. As a result, these intrinsics can't be imported.

This teaches the GlobalISelEmitter to recognize these as pointers rather than
scalars.

Differential Revision: https://reviews.llvm.org/D65756

llvm-svn: 369455