kbuild: move ".config not found!" message from Kconfig to Makefile

If you run "make" in a pristine source tree, currently Kbuild will
start to build Kconfig to let it show the error message.

It would be more straightforward to check it in Makefile and let
it fail immediately.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -628,8 +628,14 @@ ifeq ($(may-sync-config),1)
 # because some architectures define CROSS_COMPILE there.
 -include include/config/auto.conf.cmd
 
-# To avoid any implicit rule to kick in, define an empty command
-$(KCONFIG_CONFIG): ;
+$(KCONFIG_CONFIG):
+	@echo >&2 '***'
+	@echo >&2 '*** Configuration file "$@" not found!'
+	@echo >&2 '***'
+	@echo >&2 '*** Please run some configurator (e.g. "make oldconfig" or'
+	@echo >&2 '*** "make menuconfig" or "make xconfig").'
+	@echo >&2 '***'
+	@/bin/false
 
 # The actual configuration files used during the build are stored in
 # include/generated/ and include/config/. Update them if .config is newer than

scripts/kconfig/conf.c

@@ -488,7 +488,6 @@ int main(int ac, char **av)
 	const char *progname = av[0];
 	int opt;
 	const char *name, *defconfig_file = NULL /* gcc uninit */;
-	struct stat tmpstat;
 	int no_conf_write = 0;
 
 	tty_stdio = isatty(0) && isatty(1);
@@ -560,18 +559,6 @@ int main(int ac, char **av)
 	name = av[optind];
 	conf_parse(name);
 	//zconfdump(stdout);
-	if (sync_kconfig) {
-		name = conf_get_configname();
-		if (stat(name, &tmpstat)) {
-			fprintf(stderr, "***\n"
-				"*** Configuration file \"%s\" not found!\n"
-				"***\n"
-				"*** Please run some configurator (e.g. \"make oldconfig\" or\n"
-				"*** \"make menuconfig\" or \"make xconfig\").\n"
-				"***\n", name);
-			exit(1);
-		}
-	}
 
 	switch (input_mode) {
 	case defconfig: