[AMDGPU] Do not internalize ASan device library functions.

ASan device library functions (those starts with the prefix __asan_)
are at the moment undergoing through undesired optimizations due to
internalization. Hence, in order to avoid such undesired optimizations
on ASan device library functions, do not internalize them in the first
place.

Reviewed By: yaxunl

Differential Revision: https://reviews.llvm.org/D110468