short_types: relicense to public domain.

We really want everyone to be using these; establishing conventions
helps all code, so make it the most liberal license possible.  It's
all my code, so I can do this unilaterally.

ccan/short_types/LICENSE

@@ -1 +0,0 @@
-../../licenses/LGPL-2.1

ccan/short_types/_info

@@ -65,7 +65,7 @@
  *		return 0;
  *	}
  *
- * License: LGPL (v2.1 or any later version)
+ * License: Public domain
  * Author: Rusty Russell <rusty@rustcorp.com.au>
  */
 int main(int argc, char *argv[])