util/ectool: Update Makefile

- Add a help target
- Add the -Wshadow and -Werror options
- Add a way to disable -Werror

Signed-off-by: Martin Roth <martin@coreboot.org>
Change-Id: I0d9fe5beb3a2e103a0bf4603712c3a5ed15f93be
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50850
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

util/ectool/Makefile

@@ -1,7 +1,8 @@
 ## SPDX-License-Identifier: GPL-2.0-only
 
 CC = gcc
-CFLAGS = -O2 -Wall -Wextra
+WERROR=-Werror
+CFLAGS = -O2 -Wall -Wextra -Wshadow $(WERROR)
 PROGRAM = ectool
 INSTALL = /usr/bin/env install
 PREFIX  = /usr/local
@@ -31,4 +32,10 @@ distclean: clean
 %.o: %.c
 	$(CC) $(CFLAGS) -c $^ -I. -o $@
 
-.PHONY: all install clean distclean
+help:
+	@echo "${PROGRAM}: Dump RAM of Embedded Controller (EC)"
+	@echo "Targets: all, clean, distclean, help, install"
+	@echo "To disable warnings as errors, run make as:"
+	@echo "  make all WERROR=\"\""
+
+.PHONY: all clean distclean help install