Adds support for GPL symbols (those exported with EXPORT_SYMBOL_GPL instead
of EXPORT_SYMBOL) to insmod. This is a backport from later busybox versions,
it corresponds to revision 7301 in the busybox svn repository:

http://www.busybox.net/cgi-bin/viewcvs.cgi/trunk/busybox/modutils/insmod.c?rev=7301&view=markup
--- busybox-0.60.5/insmod.c	2002-09-16 06:30:10.000000000 +0100
+++ busybox-0.60.5-symbols/insmod.c	2005-06-21 20:58:57.000000000 +0100
@@ -607,6 +607,8 @@
 
 static void arch_create_got (struct obj_file *f);
 
+static int obj_gpl_license(struct obj_file *f, const char **license);
+
 #ifdef BB_FEATURE_NEW_MODULE_INTERFACE
 static int arch_init_module (struct obj_file *f, struct new_module *);
 #endif
@@ -1710,12 +1712,29 @@
 	size_t i;
 	int used = 0;
 
+	int gpl;
+	gpl = obj_gpl_license(f, NULL) == 0;
+
 	for (i = 0, s = syms; i < nsyms; ++i, ++s) {
 
 		/* Only add symbols that are already marked external.  If we
 		   override locals we may cause problems for argument initialization.
 		   We will also create a false dependency on the module.  */
 		struct obj_symbol *sym;
+		char *name;
+ 
+		/* GPL licensed modules can use symbols exported with
+		 * EXPORT_SYMBOL_GPL, so ignore any GPLONLY_ prefix on the
+		 * exported names.  Non-GPL modules never see any GPLONLY_
+		 * symbols so they cannot fudge it by adding the prefix on
+		 * their references.
+		 */
+		if (strncmp((char *)s->name, "GPLONLY_", 8) == 0) {
+			if (gpl)
+				((char *)s->name) += 8;
+			else
+				continue;
+		}
 
 		sym = obj_find_symbol(f, (char *) s->name);
 		if (sym && !ELFW(ST_BIND) (sym->info) == STB_LOCAL) {