failing to link custom kernel on 10.0-release

[Benjamin Kaduk]

With INVARIANT_SUPPORT added, the kernel builds.

On boot, I get
panic: mtx_lock_spin: recursed on non-recursive mutex cnputs_mtx @
        /usr/src/sys/kern/kern_cons.c:500

I guess I get to rebuild with WITNESS_SKIPSPIN.

-Ben