Makefile: Suppress unwanted 'echo' output

Add a 'echo' command which can be called to generate output. If V=0 then
it is suppressed. This drops the unwanted output when V=0.

Signed-off-by: Simon Glass <sjg@chromium.org>
BUG=chromium:680243
BRANCH=none
TEST=V=0 emerge-reef chromeos-ec; See that the BUILD lines are gone

Change-Id: Ie4474024c84345d427f4d95a9ff194dc740f860f
Reviewed-on: https://chromium-review.googlesource.com/427364
Commit-Ready: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>

Makefile.rules

@@ -33,10 +33,12 @@ _dir_y_create := $(foreach d,$(dirs-y),$(shell [ -d $(out)/$(BLD)/$(d) ] || \
 # (warnings/errors only). Use echo thus: $(call echo,"stuff  to  echo")
 ifeq ($(V),0)
 Q := @
+echo = echo -n;
 quiet = echo -n; $(cmd_$(1))
 silent = 1>/dev/null
 silent_err = 2>/dev/null
 else
+echo = echo $(1);
 ifeq ($(V),)
 Q := @
 quiet = @echo '  $(2)' $(subst $(out)/,,$@) ; $(cmd_$(1))
@@ -176,7 +178,7 @@ test-targets=$(foreach t,$(test-list-y),test-$(t))
 ifeq "$(CONFIG_COMMON_RUNTIME)" "y"
 $(test-targets): test-%:
 	@set -e ; \
-	echo "  BUILD   $(out)/$*" ; \
+	$(call echo,"  BUILD   $(out)/$*") \
 	$(MAKE) --no-print-directory BOARD=$(BOARD) PROJECT=$* \
 	        V=$(V) out=$(out)/$* TEST_BUILD=y; \
 	cp $(out)/$*/$*.bin $(out)/test-$*.bin
@@ -192,7 +194,7 @@ run-test-targets=$(foreach t,$(test-list-host),run-$(t))
 
 $(host-test-targets): host-%:
 	@set -e ; \
-	echo "  BUILD   host - build/host/$*" ; \
+	$(call echo,"  BUILD   host - build/host/$*") \
 	$(MAKE) --no-print-directory BOARD=host PROJECT=$* \
 	        V=$(V) out=build/host/$* TEST_BUILD=y EMU_BUILD=y $(TEST_FLAG) \
 		CROSS_COMPILE= build/host/$*/$*.exe