bpftool: Fix memory leak in do_build_table_cb

bpftool: Fix memory leak in do_build_table_cb

[ Upstream commit fa55ef14ef4fe06198c0ce811b603aec24134bc2 ]

strdup() allocates memory for path. We need to release the memory in the
following error path. Add free() to avoid memory leak.

Fixes: 8f184732b60b ("bpftool: Switch to libbpf's hashmap for pinned paths of BPF objects")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221206071906.806384-1-linmq006@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>