[foreign] RFR: enable JIT in clang-ffi test

[Maurizio Cimadamore]

The clang-ffi test currently runs with JIT disabled. This is because 
there's a bug in how the panama-based clang sets up the call to 
"clang_toggleCrashRecovery"; this call should occur after index 
creation, not before (same as we do in JNI code).

With this fix, I've been able to run the test reliably in JIT mode.

Webrev:

http://cr.openjdk.java.net/~mcimadamore/panama/clang-ffi-jit/

P.S.
Maybe a run on MacOs would be better :-)

Cheers
Maurizio