InterfaceError on connect

Removed the bool flag from the st_mysql_options struct, since it adds 
another word in size to the memory size and shifts member memory locations
down, both of which break binary-interface compatibility.

Instead, use a flag, 2**30, in the client_options bit-field to represent
that the client should check the SSL certificate of the server.


include/mysql.h:
  Do not change the struct size.
include/mysql_com.h:
  Add a new bit-flag for client verifying server SSL certificate.
  
  Emphasize that we're not stepping on anyone else's bit/toes.
sql-common/client.c:
  Set and read the bit-field for client-side SSL-cert checking of the server.