[HIP] Enable -amdgpu-internalize-symbols

Enable -amdgpu-internalize-symbols to eliminate unused functions and global variables
for whole program to speed up compilation and improve performance.

For -fno-gpu-rdc, -amdgpu-internalize-symbols is passed to clang -cc1.

For -fgpu-rdc, -amdgpu-internalize-symbols is passed to lld.

Differential Revision: https://reviews.llvm.org/D81959