Bring across the JDWP implementation.

This compiles and links, but does nothing until we fill out the 100 or so
unimplemented methods in "debugger.cc". Note that I also need to add the
extra command-line handling for the JDWP agent stuff, and add calls from
the runtime to the various "something interesting is going on" hooks.

Change-Id: I477cf3caf9e248c384ce1d739cbfadb60e2008bc
diff --git a/src/logging.h b/src/logging.h
index d3dbcd4..2e7856e 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -169,6 +169,8 @@
   DISALLOW_COPY_AND_ASSIGN(LogMessage);
 };
 
+void HexDump(const void* address, size_t byte_count, bool show_actual_address = false);
+
 }  // namespace art
 
 #endif  // ART_SRC_LOGGING_H_