[AMDGPU] Printf runtime binding pass

[AMDGPU] Printf runtime binding pass

This pass is a port of the according pass from the HSAIL compiler.
It parses printf calls and setup runtime printf buffer.
After that it copies printf arguments to the buffer and fills in
module metadata for runtime.

Differential Revision: https://reviews.llvm.org/D24035

llvm-svn: 368592