Better diagnostic for native createCodecByName()

when passing null, provide a useful diagnostic as part of
the nullpointerexception.

Bug: 295199911
Test: atest android.mediav2.cts.CodecUnitTest
Change-Id: Ib044f4e0e0cf812ec5d08d914ae59691fea2cbff

media/jni/android_media_MediaCodec.cpp

@@ -3320,7 +3320,8 @@ static void android_media_MediaCodec_native_setup(
         JNIEnv *env, jobject thiz,
         jstring name, jboolean nameIsType, jboolean encoder, int pid, int uid) {
     if (name == NULL) {
-        jniThrowException(env, "java/lang/NullPointerException", NULL);
+        jniThrowException(env, "java/lang/NullPointerException",
+                          "No codec name specified");
         return;
     }