Fix wrong handling of Generic JNI not finding native method.

Code did not properly call JNIMethodEnd, such that locks etc
where not correctly handled.

Add a test case to jni_compiler_test.

Change-Id: If2d5c628517d65a56dd6bb5c4cabdff77c7664a1
diff --git a/test/MyClassNatives/MyClassNatives.java b/test/MyClassNatives/MyClassNatives.java
index 6e7a426..09f1783 100644
--- a/test/MyClassNatives/MyClassNatives.java
+++ b/test/MyClassNatives/MyClassNatives.java
@@ -79,4 +79,5 @@
         Object o240, Object o241, Object o242, Object o243, Object o244, Object o245, Object o246, Object o247,
         Object o248, Object o249, Object o250, Object o251, Object o252, Object o253);
 
+    native void withoutImplementation();
 }