-) Fixed a few more (much more rare) race conditions on shutdown.
-) Fixed a degenerate case if we create a server but never start it.

Fixing a very edge case where the tcp_client can crash due to race conditions on connection abortion.

-) tcp client and server should no longer starve waiting on orphans
-) proper server shutdown sequence to prevent use-after-free.

By the standard, std::function can only capture class functions, and not
class methods. For some reasons, this works under gcc however. Visual
Studio rejects it. std::mem_fn is proper template to use.

With the metadata batching changes recently, I introduced a bug whereby
the http2 stream encoder would end up not being able to set the close bit on a header frame, and instead placed it on a new data frame, which is illegal by the HTTP2 spec.

- Added ptag ignore annotation threshold
- prefixed everythig with grpc_
- removed spurious annotations in channel_create.c and client_channel.c
- removed stap_probes.h (it's generated from stap_probes.d by make)
- Updated Makefile and its template with the right way to generate stap
  probe headers from its .d definition.