Makefile,meson.build: Enable/assume -Wextra

Enable all -Wextra warnings but -Wunused-parameter. Nobody seems to
miss warnings about unused parameters and we have a lot unavoidable
occurrences in flashrom because of common interfaces.

Change-Id: Id2ece264c2d483e34019985dd3a7631c4889abe6
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/30411


Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jacob Garber <jgarber1@ualberta.ca>

Makefile

@@ -30,7 +30,7 @@ INSTALL = install
 DIFF    = diff
 PREFIX  ?= /usr/local
 MANDIR  ?= $(PREFIX)/share/man
-CFLAGS  ?= -Os -Wall -Wshadow -Wmissing-prototypes -Wwrite-strings
+CFLAGS  ?= -Os -Wall -Wextra -Wno-unused-parameter -Wshadow -Wmissing-prototypes -Wwrite-strings
 EXPORTDIR ?= .
 RANLIB  ?= ranlib
 PKG_CONFIG ?= pkg-config

meson.build

@@ -15,10 +15,8 @@ lt_version = '@0@.@1@.@2@'.format(lt_current, lt_age, lt_revision)
 warning_flags = [
   '-Wwrite-strings',
   '-Wno-unused-parameter',
-  '-Wno-sign-compare',
   '-Wno-address-of-packed-member',
   '-Wno-enum-conversion',
-  '-Wno-missing-field-initializers',
   '-Wno-missing-braces',
 ]