Ye Ol' π Shack

This rebuilds cached prepared statements if opt_reconnect is set and
this is the fire "server died during query" error.

See test/test_mysql_reconnect.cpp for example scenario and proof it
works.

Still need to run his other tests to make sure I didn't blunder
anything (regression).

I've added BUG to document what I've found so far in trying to combat
the "server gone away" bugs. I need to address the cache when
connections have dropped. :-/