r251744: amd64/vmm/io/vlapic.c:468:15: error: implicit declaration of function 'cpusetobj_ffs' is invalid in C99

Kernel build fails on recent r251744 CURRENT:

[...]
--- vlapic.o ---
/usr/src/sys/modules/vmm/../../amd64/vmm/io/vlapic.c:468:15: error:
implicit declaration of function 'cpusetobj_ffs' is invalid in C99
[-Werror,-Wimplicit-function-declaration] while ((i =
cpusetobj_ffs(&dmask)) != 0) { ^ 1 error generated.
*** [vlapic.o] Error code 1

make: stopped in /usr/src/sys/modules/vmm
1 error

make: stopped in /usr/src/sys/modules/vmm
*** Error code 2

Stop.
make: stopped in /usr/src/sys/modules
*** [modules-all] Error code 1