MFC r282076,r282104:

r282076:

Integrate tools/regression/mmap into the FreeBSD test suite as
tests/sys/kern/mmap_test

r282104:

Move tests/sys/kern/mmap_test to tests/sys/vm/mmap_test

As jhb noted, the actual mmap(2) implementation is under sys/vm, not
sys/kern/, so the correct logical place is tests/sys/vm/, not
tests/sys/kern/