genksyms: Do not expand internal types

Consider structures, unions and enums defined in the source file as
internal and do not expand them. This way, changes to e.g. struct
serial_private in drivers/tty/serial/8250_pci.c will not affect the
checksum of the pciserial_* exports.
diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c
index 6d3fda0..8a10649 100644
--- a/scripts/genksyms/genksyms.c
+++ b/scripts/genksyms/genksyms.c
@@ -40,7 +40,8 @@
 static FILE *debugfile;
 
 int cur_line = 1;
-char *cur_filename;
+char *cur_filename, *source_file;
+int in_source_file;
 
 static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,
 	   flag_preserve, flag_warnings;