Implement field watch support in JITed methods

[gita-omr]

This issue will track all the work for implementing field watch support in JITted methods (VM, compiler common code and codegens).

From @fjeremic:
"As things stand currently under full speed debug, when an agent requests a field to be watched we cannot JIT compile the method because we cannot respect the hooks for reporting accesses of the respective field. This limitation will be lifted by using the rdbar / rdbari opcodes to represent reads which have requested fields of certain types to be watched.

The JIT will generate read barriers for such fields of the correct type and the optimizer will treat them as normal loads. At codegen time we will reduce the read barrier to the load and insert a C helper call to notify the VM via a hook that a field has been read."

So far, we have the following related issues:

• Implement compiled method field watch support via read barrier and write barrier (JIT part) eclipse-openj9/openj9#2668
• Adding new IL Opcode xrdbar/xrdbari  #2812
• Agenda for Aug. 1, 2018 Compiler Architecture Meeting #2817

@andrewcraik @fjeremic @cathyzhyi @DanHeidinga @gacholio

[gita-omr]

There is OpenJ9 issue for this eclipse-openj9/openj9#2668 . So I will close this one