[8u] Request for approval: JDK-8043224: -Xcheck:jni improvements to exception checking and excessive local refs

[Poonam Bajaj Parhar]

Hello,

I'd like to backport the fix of 8043224 to 8u.

Bug: https://bugs.openjdk.java.net/browse/JDK-8043224
JDK9 changeset: 
http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/232dbf06eb07
8u webrev: http://cr.openjdk.java.net/~poonam/8043224/webrev/
Build and Test: JPRT

The fix applies cleanly to 8u.

Thanks,
Poonam