libnpth: add hash for license file

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libnpth/libnpth.hash

@@ -1,2 +1,5 @@
 # Locally calculated after checking signature
 sha256 294a690c1f537b92ed829d867bee537e46be93fbd60b16c04630fbbfcd9db3c2  npth-1.5.tar.bz2
+
+# Hash for license file:
+sha256 ce64d5f7b49ea6d80fdb6d4cdee6839d1a94274f7493dc797c3b55b65ec8e9ed  COPYING.LIB