[google] libgcov workaround for weak reference issue (issue 6276043)

[davidxl@google.com]

Ok with better naming for the dummy function such as
'__gcov_dummy_ref1'. Another choice is to let __gcov_flush calls
__gcov_dump + __gcov_reset -- but the dump_completed state needs to be
saved and restored.

David

http://codereview.appspot.com/6276043/