Followup to r273966.  Fix the build with ADAPTIVE_LOCKMGRS kernel option.

Note that the option is currently not used in any in-tree kernel
configs, including LINTs.

Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273986 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Don't check for a NULL curthread.  curthread hasn't been NULL after early
boot since 5.0.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273987 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f