[tilegx] Fix profiling inftrastructure bug.

  1. keep mcontext the same as tilegx kernel.
  2. fix bug in ProfileEntryHookStub::Generate.
[tilegx] A couple of 64-bit bit operation fixes.
[tilegx] Fix critical bug on JS frame setup.

  temp register "tt" is used by MemOperand implicitly, we should use
tt2 outside of MemOperand to avoid reg collision.