libbpf: Fix glob_syms memory leak in bpf_linker

libbpf: Fix glob_syms memory leak in bpf_linker

[ Upstream commit 8cb125566c40b7141d8842c534f0ea5820ee3d5c ]

glob_syms array wasn't freed on bpf_link__free(). Fix that.

Fixes: a46349227cd8 ("libbpf: Add linker extern resolution support for functions and global variables")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-6-andrii@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>