Some environments require some variation on "make defconfig" to initialize
the .config file.  This commit therefore adds a --defconfig argument to
allow this to be specified.  The default value is of course "defconfig".
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>