Fix dump_gcov
Fix dump_gcov

Currently an invocation like

dump_gcov ./sort.gcda

 fails with

F20210903 16:42:21.612994 2065129 profile_reader.cc:114] Check failed: gcov_read_unsigned() == absl::GetFlag(FLAGS_gcov_version) (2 vs. 875575082) ./sort.gcda
*** Check failure stack trace: ***
Aborted (core dumped)

There is no way to pass the version to dump_gcov and it makes more sense to just use
the version encoded in the file.

google/autofdo,google/autofdo,google/autofdo