move security_mmap_addr() to saner place

it really should be done by get_unmapped_area(); that cuts down on
the amount of callers considerably and it's the right place for
that stuff anyway.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --cc mm/mmap.c
Simple merge

diff --cc mm/mremap.c
Simple merge