build: unify compiler warnings

configure.ac

@@ -60,35 +60,6 @@ else
 fi
 AC_SUBST(PPPD_PLUGIN_DIR)
 
-AC_ARG_ENABLE(more-warnings,
-AS_HELP_STRING([--enable-more-warnings], [Maximum compiler warnings]), set_more_warnings="$enableval",set_more_warnings=yes)
-AC_MSG_CHECKING(for more warnings, including -Werror)
-if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
-	AC_MSG_RESULT(yes)
-	CFLAGS="-Wall -Werror -std=gnu89 $CFLAGS"
-
-	for option in -Wshadow -Wmissing-declarations -Wmissing-prototypes \
-		      -Wdeclaration-after-statement -Wstrict-prototypes \
-		      -Wfloat-equal -Wno-unused-parameter -Wno-sign-compare \
-		      -fno-strict-aliasing; do
-		SAVE_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS $option"
-		AC_MSG_CHECKING([whether gcc understands $option])
-		AC_TRY_COMPILE([], [],
-			has_option=yes,
-			has_option=no)
-		if test $has_option = no; then
-			CFLAGS="$SAVE_CFLAGS"
-		fi
-		AC_MSG_RESULT($has_option)
-		unset has_option
-		unset SAVE_CFLAGS
-	done
-	unset option
-else
-	AC_MSG_RESULT(no)
-fi
-
 AC_ARG_WITH(docs, AC_HELP_STRING([--with-docs], [Build ModemManager documentation]))
 AM_CONDITIONAL(WITH_DOCS, test "x$with_docs" = "xyes")
 case $with_docs in
@@ -112,6 +83,8 @@ case $with_tests in
         ;;
 esac
 
+NM_COMPILER_WARNINGS
+
 AC_CONFIG_FILES([
 Makefile
 marshallers/Makefile