Makefile: Fix verbose builds on Windows

Commit <ee1ba6d4

> ("Makefile: Support totally quiet output with -s")
broke verbose (V=1) builds on Windows. This patch fixes it by adding
helpers to silence echo prints in a OS-dependent way.

Change-Id: I24669150457516e9fb34fa32fa103398efe8082d
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Makefile

@@ -78,12 +78,12 @@ ifeq (${V},0)
         CHECKCODE_ARGS	+=	--no-summary --terse
 else
         Q:=
-        ECHO:=@\#
+        ECHO:=$(ECHO_QUIET)
 endif
 
 ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
         Q:=@
-        ECHO:=@\#
+        ECHO:=$(ECHO_QUIET)
 endif
 
 export Q ECHO

make_helpers/unix.mk

 #
-# Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
-#
 
 # Trusted Firmware shell command definitions for a Unix style environment.
 
@@ -11,6 +10,7 @@ ifndef UNIX_MK
     UNIX_MK := $(lastword $(MAKEFILE_LIST))
 
     ECHO_BLANK_LINE := echo
+    ECHO_QUIET := @\#
 
     DIR_DELIM := /
     PATH_SEP := :

make_helpers/windows.mk

 #
-# Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
-#
 
 # OS specific parts for builds in a Windows_NT environment. The
 # environment variable OS is set to Windows_NT on all modern Windows platforms
@@ -14,6 +13,7 @@ ifndef WINDOWS_MK
     WINDOWS_MK := $(lastword $(MAKEFILE_LIST))
 
     ECHO_BLANK_LINE := @cmd /c echo.
+    ECHO_QUIET := @rem
     DIR_DELIM := $(strip \)
     BIN_EXT   := .exe
     PATH_SEP  := ;