Implement automatic module license checking according to new GNU

guidelines.

	* grub-core/kern/dl.c (grub_dl_check_license): New function.
	(grub_dl_load_core): Use grub_dl_check_license.
	* include/grub/dl.h (GRUB_MOD_SECTION): New macro.
	(GRUB_MOD_LICENSE): Likewise.
	(GRUB_MOD_DUAL_LICENSE): Likewise.
	All modules updated.

grub-core/commands/i386/cmostest.c

@@ -21,6 +21,8 @@
 #include <grub/misc.h>
 #include <grub/cmos.h>
 
+GRUB_MOD_LICENSE ("GPLv3+");
+
 static grub_err_t
 parse_args (int argc, char *argv[], int *byte, int *bit)
 {