kconfig: make parent directories for the saved .config as needed

With menuconfig / nconfig, users can input any file path from the
"Save" menu, but it fails if the parent directory does not exist.

Why not create the parent directory automatically. I think this is
a user-friendly behavior.

I changed the error messages in menuconfig / nconfig.

"Nonexistent directory" is no longer the most likely reason of the
failure. Perhaps, the user specified the existing directory, or
attempted to write to the location without write permission.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 399973e..d7bd353 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -881,6 +881,9 @@ int conf_write(const char *name)
 		return -1;
 	}
 
+	if (make_parent_dir(name))
+		return -1;
+
 	env = getenv("KCONFIG_OVERWRITECONFIG");
 	if (env && *env) {
 		*tmpname = 0;