Build: Correct Unix specific echo commands

Some recent changes have added direct use of the echo command without
parameters.  This fails on a Windows shell, because echo without
parameters reports the mode ("ECHO is on").
This is corrected using the ECHO_BLANK_LINE macro already provided
for that purpose.

Change-Id: I5fd7192861b4496f6f46b4f096e80a752cd135d6
Signed-off-by: Evan Lloyd <evan.lloyd@arm.com>

Makefile

@@ -653,18 +653,18 @@ ${BUILD_PLAT}/${FIP_NAME}: ${FIP_DEPS} ${FIPTOOL}
 ifneq (${GENERATE_COT},0)
 fwu_certificates: ${FWU_CRT_DEPS} ${CRTTOOL}
 	${Q}${CRTTOOL} ${FWU_CRT_ARGS}
-	@echo
+	@${ECHO_BLANK_LINE}
 	@echo "Built $@ successfully"
 	@echo "FWU certificates can be found in ${BUILD_PLAT}"
-	@echo
+	@${ECHO_BLANK_LINE}
 endif
 
 ${BUILD_PLAT}/${FWU_FIP_NAME}: ${FWU_FIP_DEPS} ${FIPTOOL}
 	${Q}${FIPTOOL} create ${FWU_FIP_ARGS} $@
 	${Q}${FIPTOOL} info $@
-	@echo
+	@${ECHO_BLANK_LINE}
 	@echo "Built $@ successfully"
-	@echo
+	@${ECHO_BLANK_LINE}
 
 fiptool: ${FIPTOOL}
 fip: ${BUILD_PLAT}/${FIP_NAME}

make_helpers/build_macros.mk

@@ -347,9 +347,9 @@ $(DUMP): $(ELF)
 $(BIN): $(ELF)
 	@echo "  BIN     $$@"
 	$$(Q)$$(OC) -O binary $$< $$@
-	@echo
+	@${ECHO_BLANK_LINE}
 	@echo "Built $$@ successfully"
-	@echo
+	@${ECHO_BLANK_LINE}
 
 .PHONY: bl$(1)
 bl$(1): $(BIN) $(DUMP)