v.io/x/jni: implement runt BlessingStore functions for JNI

These are newly added interface functions for caching security.Discharges.
Since we don't support Discharges yet, punting on these interface
functions.

Change-Id: I861e17b049ad1f1d06df2092a08953727100e1d5
diff --git a/v23/security/store.go b/v23/security/store.go
index f61287e..f4fe309 100644
--- a/v23/security/store.go
+++ b/v23/security/store.go
@@ -167,6 +167,18 @@
 	return ret
 }
 
+func (s *blessingStore) CacheDischarge(discharge security.Discharge, caveat security.Caveat, impetus security.DischargeImpetus) {
+	panic("BlessingStore.CacheDischarge() unimplemented in Java")
+}
+
+func (s *blessingStore) ClearDischarges(discharges ...security.Discharge) {
+	panic("BlessingStore.ClearDischarges() unimplemented in Java")
+}
+
+func (s *blessingStore) Discharge(caveat security.Caveat, impetus security.DischargeImpetus) security.Discharge {
+	panic("BlessingStore.Discharge() unimplemented in Java")
+}
+
 func (r *blessingStore) DebugString() string {
 	env, freeFunc := jutil.GetEnv()
 	defer freeFunc()