Makefile: add savedefconfig target.

This writes a file called 'defconfig' which contains only the deltas from
the default configuration.  It's suitable for use as an input defconfig file
for later builds.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
1 file changed