RFR: 8213845: ARM32: Interpreter doesn't call result handler after native calls

[Nick Gasson]

Hi,

Could someone help me review this patch please?

Bug: https://bugs.openjdk.java.net/browse/JDK-8213845
Webrev: http://cr.openjdk.java.net/~njian/8213845/webrev.0/

This fixes a failure of the test runtime/BoolReturn/JNIBooleanTest.java
caused by a native method returning a value outside 0..1 as a
jboolean which is then interpreted as Java boolean false. Other
platforms map all non-zero values to 1 when a native method
returns boolean.

This is basically the same as bug 8209637 on S390 but the fix for
ARM32 is more complicated as this platform didn't previously use
the "result handler" mechanism.

Changes:

* We now call the result handler in the interpreter. Restoring
  oop results from the stack is now handled here rather than
  directly in the native wrapper. Boolean normalisation is
  performed if the result type is T_BOOLEAN otherwise the handler
  does nothing as before.

* Implemented MacroAssembler::c2bool to match other platforms.

* Call c2bool at the end of SharedRuntime::generate_native_wrapper
  to handle boolean results in compiled code.

I've checked that this causes no new Jtreg regressions.

Thanks!
Nick