Kbuild supports saving output files in a separate directory.
But the build directory must be created beforehand. For example,

  $ mkdir -p dir/to/store/output/files
  $ make O=dir/to/store/output/files defconfig

Creating a build directory automatically would be useful.

[ imported from Linux Kernel, commit 1c9e70a55b08 ]
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>