glsl: Use the utility function to copy symbols between symbol tables
This effectively factorizes a couple of similar routines. v2 (Neil Roberts): Non-trivial rebase on master Reviewed-by:Kenneth Graunke <kenneth@whitecape.org> Signed-off-by:
Eduardo Lima Mitev <elima@igalia.com> Signed-off-by:
Neil Roberts <nroberts@igalia.com>