JRE-411 CPlatformWindow leaks via JNI local

review: JR-CR-173

(cherry picked from commit 2cdffc6)
diff --git a/src/macosx/native/sun/awt/AWTView.m b/src/macosx/native/sun/awt/AWTView.m
index c79badc..5a0209b 100644
--- a/src/macosx/native/sun/awt/AWTView.m
+++ b/src/macosx/native/sun/awt/AWTView.m
@@ -494,6 +494,7 @@
     } else {
         NSLog(@"m_cPlatformView is null");
     }
+    (*env)->DeleteLocalRef(env, platformWindow);
 }
 
 - (void) resetTrackingArea {