[11u] RFR: 8212160: JVMTI agent crashes with "assert(_value != 0LL) failed: resolving NULL _value"

[Lindenmaier, Goetz]

Hi

I am downporting this for parity with 11.0.10-oracle.

http://cr.openjdk.java.net/~goetz/wr20/8212160-jvmti_crash_resolving-jdk11/01/
I had to resolve and fis in quite some places:

src/hotspot/share/code/nmethod.cpp
Resolved. Few differences in code, e.g. MutexLocker --> MutexLockerEx.

Added 'this' to call of JvmtiDeferredEvent::compiled_method_unload_event()

src/hotspot/share/code/nmethod.hpp
Trivial, resolved.

src/hotspot/share/prims/jvmtiCodeBlobEvents.cpp
Resolved. Few differences in code, e.g. MutexLocker --> MutexLockerEx.

I removed NMethodIterator::only_alive_and_not_unloading and call next_alive instead.
The NMethodIterator differs in head a lot.

src/hotspot/share/prims/jvmtiExport.cpp
Resolved. Few differences in code, e.g. MutexLocker --> MutexLockerEx.

I added void JvmtiExport::post_compiled_method_load(JvmtiEnv* env, nmethod *nm)
from head which is called in 

src/hotspot/share/prims/jvmtiExport.hpp
Resolved. Deleted method has different arguments.

src/hotspot/share/prims/jvmtiImpl.hpp
Resolved.

src/hotspot/share/runtime/serviceThread.cpp
Context different.

Please review.
https://bugs.openjdk.java.net/browse/JDK-8212160
https://hg.openjdk.java.net/jdk/jdk/rev/366c0f357ee6

Best regards,
  Goetz