RFR 8229919: Support JNI Critical functions in object pinning API on x86_32 platforms

[Zhengyu Gu]

Please review this patch that supports JNI critical functions in object 
pinning capable GCs on x86_32 platforms.

Bug: https://bugs.openjdk.java.net/browse/JDK-8229919
Webrev: http://cr.openjdk.java.net/~zgu/JDK-8229919/webrev.00/

Test:
   hotspot_gc_shenandoah (fastdebug and release) with 32-bit VM on Linux 
x86_64.
   hotspot_gc, hotspot_runtime and hotspot_compiler
   Submit tests in progress.

Thanks,

-Zhengyu