scripts/diffconfig.sh: ensure config/conf is built

diffconfig.sh runs ./scripts/config/conf, but it does not get built
with 'make {menu,x,n}config.  Call 'make ./scripts/config/conf' to
ensure it's been built befpre running it.

Signed-off-by: Eneas U de Queiroz <cotequeiroz@gmail.com>

scripts/diffconfig.sh

@@ -8,6 +8,7 @@ grep '^CONFIG_DEVEL=y' .config >> tmp/.diffconfig.head
 grep '^CONFIG_TOOLCHAINOPTS=y' .config >> tmp/.diffconfig.head
 grep '^CONFIG_BUSYBOX_CUSTOM=y' .config >> tmp/.diffconfig.head
 grep '^CONFIG_TARGET_PER_DEVICE_ROOTFS=y' .config >> tmp/.diffconfig.head
+make -s ./scripts/config/conf
 ./scripts/config/conf --defconfig=tmp/.diffconfig.head -w tmp/.diffconfig.stage1 Config.in >/dev/null
 ./scripts/kconfig.pl '>+' tmp/.diffconfig.stage1 .config >> tmp/.diffconfig.head
 ./scripts/config/conf --defconfig=tmp/.diffconfig.head -w tmp/.diffconfig.stage2 Config.in >/dev/null