test_build.sh: Use multiple cores if Make is used

Signed-off-by: Felix Singer <felixsinger@posteo.net>
Change-Id: Ia67e9202e49f1b4bc3301399a8ec741ac01c3ce0
Reviewed-on: https://review.coreboot.org/c/flashrom/+/67244
Reviewed-by: Thomas Heijligen <src@posteo.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

test_build.sh

@@ -28,7 +28,7 @@ fi
 
 build_make () {
 	make clean
-	make CONFIG_EVERYTHING=yes
+	make -j $(nproc) CONFIG_EVERYTHING=yes
 
 	# In case of clang analyzer we don't want to run it on
 	# each programmer individually. Thus, just return here.
@@ -39,7 +39,7 @@ build_make () {
 	for option in ${make_programmer_opts}; do
 		echo "Building ${option}"
 		make clean
-		make CONFIG_NOTHING=yes CONFIG_${option}=yes
+		make -j $(nproc) CONFIG_NOTHING=yes CONFIG_${option}=yes
 	done
 }