Add support for tracing Java method entry/exit in emulator.

This is part of a larger change and depends on changes to the
kernel and the emulator tracing code.  The code used to work by
by writing to a "magic page" which the emulator would notice
because it watches every load and store.  But the emulator lost
the ability to watch every load and store with the latest update
to qemu.  So the new code sets up a memory-mapped page that the
emulator watches.  This is cleaner and more efficient anyway.
1 file changed