libsemanage: Fix null pointer dereference in semanage_module_key_destroy

If modkey is NULL, semanage_module_key_destroy() would still try to
initialize a modkey after freeing it.

Signed-off-by: Yuli Khodorkovskiy <ykhodorkovskiy@tresys.com>
Signed-off-by: James Carter <jwcart2@tycho.nsa.gov>
1 file changed