modpost: re-add -e to set external_module flag

Previously, the -i option had two functions; load a symbol dump file,
and set the external_module flag.

I want to assign a dedicate option for each of them.

Going forward, the -i is used to load a symbol dump file, and the -e
to set the external_module flag.

With this, we will be able to use -i for loading in-kernel symbols.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/Makefile.modpost

@@ -79,6 +79,10 @@ src := $(obj)
 # Include the module's Makefile to find KBUILD_EXTRA_SYMBOLS
 include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \
              $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile)
+
+# modpost option for external modules
+MODPOST += -e
+
 endif
 
 # modpost options for modules (both in-kernel and external)

scripts/mod/modpost.c

@@ -2552,10 +2552,12 @@ int main(int argc, char **argv)
 	struct dump_list *dump_read_start = NULL;
 	struct dump_list **dump_read_iter = &dump_read_start;
 
-	while ((opt = getopt(argc, argv, "i:mnsT:o:awENd:")) != -1) {
+	while ((opt = getopt(argc, argv, "ei:mnsT:o:awENd:")) != -1) {
 		switch (opt) {
-		case 'i':
+		case 'e':
 			external_module = 1;
+			break;
+		case 'i':
 			*dump_read_iter =
 				NOFAIL(calloc(1, sizeof(**dump_read_iter)));
 			(*dump_read_iter)->file = optarg;