Plug a memory leak.

Obtained from:	DragonFlyBSD (commit 5119ece)
MFC after:	2 weeks
Fix `make depend` in sys/modules

Differential Revision:	https://reviews.freebsd.org/D1338
Reviewed by:	delphij
Approved by:	delphij
Merge remote-tracking branch 'freebsd/master' into hardened/current/master