[Flang][Driver] Enable gpulibc/nogpulibc options for Flang, which allows...

[Flang][Driver] Enable gpulibc/nogpulibc options for Flang, which allows linking of GPU LIBC for the fortran and OpenMP runtime (#77135)

This patch seeks to add the -gpulibc and -nogpulibc for Flang, which
allows the linking of the GPU libc library, this allows the use of
memcpy and other useful library functions for GPU.

In particular, this allows the Fortran runtime (written in C++) to be
compiled for offload and then linked against the GPU LIBC library via
this option to resolve memcpy and other C library functions that the
fortran runtime depends on for AMD GPU devices (and likely other GPU
devices).

This is the current method I've tested and found to be able to utilise
the Fortran runtime when compiled for AMD GPU, albeit it requires
compiling libc for GPU and then the Fortran runtime for GPU, so not
particularly straight forward or user friendly yet.

Activating this option will allow the subset of C functions to also be
utilised for GPU in other C/C++ based Fortran libraries if any are made
when linking against GPU libc.