[Driver] Render target options (e.g. -fuse-init-array) for -fembed-bitcode

Modern ELF platforms use -fuse-init-array to emit .init_array instead of
.ctors .  ld.bfd and gold --ctors-in-init-array merge .init_array and
.ctors into .init_array but lld doesn't do that.

If crtbegin*.o crtend*.o don't provide .ctors/.dtors, such .ctors in
user object files can lead to crash (see PR42002. The first and the last
elements in .ctors/.dtors are ignored - they are traditionally provided
by crtbegin*.o crtend*.o).

Call addClangTargetOptions() to ensure -fuse-init-array is rendered on
modern ELF platforms. On Hexagon, this renders -target-feature
+reserved-r19 for -ffixed-r19.

Reviewed By: compnerd

Differential Revision: https://reviews.llvm.org/D62509

llvm-svn: 362052