Pull kbuild fix from Michal Marek:
"One fix for for make headers_install/headers_check to not require make
3.81. The requirement has been accidentally introduced in 3.7."
* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
kbuild: fix make headers_check with make 3.80