modpost: load KBUILD_EXTRA_SYMBOLS files in order

Currently, modpost reads extra symbol dump files in the reverse order.
If '-e foo -e bar' is given, modpost reads bar, foo, in this order.

This is probably not a big deal, but there is no good reason to reverse
the order. Read files in the given order.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/mod/modpost.c

@@ -2555,8 +2555,8 @@ int main(int argc, char **argv)
 	int opt;
 	int err;
 	int n;
-	struct ext_sym_list *extsym_iter;
 	struct ext_sym_list *extsym_start = NULL;
+	struct ext_sym_list **extsym_iter = &extsym_start;
 
 	while ((opt = getopt(argc, argv, "i:e:mnsT:o:awENd:")) != -1) {
 		switch (opt) {
@@ -2566,11 +2566,9 @@ int main(int argc, char **argv)
 			break;
 		case 'e':
 			external_module = 1;
-			extsym_iter =
-			   NOFAIL(malloc(sizeof(*extsym_iter)));
-			extsym_iter->next = extsym_start;
-			extsym_iter->file = optarg;
-			extsym_start = extsym_iter;
+			*extsym_iter = NOFAIL(calloc(1, sizeof(**extsym_iter)));
+			(*extsym_iter)->file = optarg;
+			extsym_iter = &(*extsym_iter)->next;
 			break;
 		case 'm':
 			modversions = 1;
@@ -2610,10 +2608,12 @@ int main(int argc, char **argv)
 	if (kernel_read)
 		read_dump(kernel_read, 1);
 	while (extsym_start) {
+		struct ext_sym_list *tmp;
+
 		read_dump(extsym_start->file, 0);
-		extsym_iter = extsym_start->next;
+		tmp = extsym_start->next;
 		free(extsym_start);
-		extsym_start = extsym_iter;
+		extsym_start = tmp;
 	}
 
 	while (optind < argc)