[8u Backport] RFR: 8177429: possible null pointer dereference defects

[Rahul Raghavan]

Hi,

Request for approval -  
<webrev.01> - http://cr.openjdk.java.net/~rraghavan/8175345/webrev.01/

<jbs> - '49 Null pointer dereference defect groups in 21 files' - 
    https://bugs.openjdk.java.net/browse/JDK-8177429
Backport of -
    https://bugs.openjdk.java.net/browse/JDK-8175345

With 8175345, the changes done in jdk9 were reviewed in open and committed.
<RFR thread> http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2017-March/025798.html
<changeset> http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/55e3f1f3d0a7

This backport fix is same as in jdk9.

Thanks,
Rahul