Global JNI references aren't handled right.

Fix for 1.5 beta2 hopefully.

Probably need to use JNI interception table and not use the class_tag
from JVMTI heap iterate functions.

The Global ref is always using the refered object as the GLOBal ref, and the
class as the Global ref.

cruella<54> fgrep 50000327 java.hprof.txt
ROOT 50000327 (kind=<JNI global ref>, id=5000011e, trace=300021)
OBJ 50000327 (sz=304, trace=300000, class=java.lang.Object@5000000e)
cruella<55> fgrep 5000011e java.hprof.txt
ROOT 50000327 (kind=<JNI global ref>, id=5000011e, trace=300021)
ROOT 5000011e (kind=<system class>, name=java.net.URLClassLoader$1)
CLS 5000011e (name=java.net.URLClassLoader$1, trace=300021)