trees: use multiple threads to build cbutils

Signed-off-by: Leah Rowe <leah@libreboot.org>

script/trees

@@ -177,7 +177,7 @@ check_coreboot_utils()
 
 		utilmode=""
 		[ -z "$mode" ] || utilmode="clean"
-		x_ make -C "$utilsrcdir" $utilmode
+		x_ make -C "$utilsrcdir" $utilmode -j$threads
 		[ -z "$mode" ] && [ ! -f "$utilelfdir/$util" ] && \
 			x_ mkdir -p "$utilelfdir" && \
 			x_ cp "$utilsrcdir/$util" "elf/$util/$1"