[AMDGPU] Ported and adopted AMDLibCalls pass

The pass does simplifications of well known AMD library calls.
If given -amdgpu-prelink option it works in a pre-link mode which
allows to reference new library functions which will be linked in
later.

In addition it also used to process traditional AMD option
-fuse-native which allows to replace some of the functions with
their fast native implementations from the library.

The necessary glue to pass the prelink option and translate
-fuse-native is to be added to the driver.

Differential Revision: https://reviews.llvm.org/D36436

llvm-svn: 310731