build system: mark sub-make invocations as parallelizable

We rely on gnu make, so we can expect the jobserver to be around in
parallel builds, too. Avoids some make warnings and slightly speeds up
the build if those sub-makes are executed (eg for arm-trusted-firmware
and vboot).

Change-Id: I0e6a77f2813f7453d53e88e0214ad8c1b8689042
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/18263
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>
diff --git a/Makefile b/Makefile
index 2973030..4a05890 100644
--- a/Makefile
+++ b/Makefile
@@ -168,7 +168,7 @@
 .SECONDEXPANSION:
 
 $(KCONFIG_AUTOHEADER): $(KCONFIG_CONFIG)
-	$(MAKE) oldconfig
+	+$(MAKE) oldconfig
 
 # Add a new class of source/object files to the build system
 add-class= \
diff --git a/Makefile.inc b/Makefile.inc
index d609ac4..2267f32 100644
--- a/Makefile.inc
+++ b/Makefile.inc
@@ -274,7 +274,7 @@
 # arg2: output
 cbfs-files-processor-defconfig= \
 	$(eval $(2): $(1) $(obj)/build.h; \
-		printf "    CREATE     $(2) (from $(1))\n"; \
+		+printf "    CREATE     $(2) (from $(1))\n"; \
 		printf "\# This image was built using coreboot " > $(2).tmp && \
 		grep "\<COREBOOT_VERSION\>" $(obj)/build.h |cut -d\" -f2 >> $(2).tmp && \
 		$(MAKE) DOTCONFIG=$(1) DEFCONFIG=$(2).tmp2 savedefconfig && \
@@ -486,7 +486,7 @@
 IFDTOOL:=$(objutil)/ifdtool/ifdtool
 $(IFDTOOL):
 	@printf "    Compile IFDTOOL\n"
-	$(MAKE) -C $(top)/util/ifdtool
+	+$(MAKE) -C $(top)/util/ifdtool
 	cp -a $(top)/util/ifdtool/ifdtool $@
 
 IFDFAKE:=$(objutil)/ifdfake/ifdfake
diff --git a/src/arch/arm64/Makefile.inc b/src/arch/arm64/Makefile.inc
index 78ea427..c6c0280 100644
--- a/src/arch/arm64/Makefile.inc
+++ b/src/arch/arm64/Makefile.inc
@@ -172,8 +172,8 @@
 BL31 := $(obj)/bl31.elf
 
 $(BL31): $(obj)/build.h
-	@printf "    MAKE       $(subst $(obj)/,,$(@))\n"
-	CROSS_COMPILE="$(CROSS_COMPILE_arm64)" \
+	printf "    MAKE       $(subst $(obj)/,,$(@))\n"
+	+CROSS_COMPILE="$(CROSS_COMPILE_arm64)" \
 	CFLAGS="$(BL31_CFLAGS)" \
 	LDFLAGS="$(BL31_LDFLAGS)" \
 	$(MAKE) -C $(BL31_SOURCE) $(BL31_MAKEARGS) $(BL31_TARGET)
diff --git a/src/vboot/Makefile.inc b/src/vboot/Makefile.inc
index c03d639..fb373c3 100644
--- a/src/vboot/Makefile.inc
+++ b/src/vboot/Makefile.inc
@@ -95,8 +95,8 @@
 VBOOT_CFLAGS += -DVBOOT_DEBUG
 
 $(VB2_LIB): $(obj)/config.h
-	@printf "    MAKE       $(subst $(obj)/,,$(@))\n"
-	$(Q)FIRMWARE_ARCH=$(VB_FIRMWARE_ARCH) \
+	printf "    MAKE       $(subst $(obj)/,,$(@))\n"
+	+FIRMWARE_ARCH=$(VB_FIRMWARE_ARCH) \
 	CC="$(CC_verstage)" \
 	CFLAGS="$(VBOOT_CFLAGS)" VBOOT2="y" \
 	$(MAKE) -C $(VBOOT_SOURCE) \