[OpenMP] Add -Bsymbolic to arguments for GNU linker

This patch adds the '-Bsymbolic' flag when we perform linking for the
offloading device. We already pass '-fvisibility=protected' but this is
not properly handled when using the bfd linker as is described in
https://maskray.me/blog/2021-05-16-elf-interposition-and-bsymbolic.
Previously this caused linker errors when creating the shared library.

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D119018