CC_send_query_append crash

Hello,

While stress testing our software to handle network
reconnects/disconnects I have run into a crash in your ODBC driver.

The crash seems to occur because CC_send_query_append crash takes a
local copy of the pointer 'self->sock' at the top of the function,
'self' is then passed around to various functions (some of which have
the side effect of setting self->sock to NULL (and deleting) if there is
a lost connection) and then the local copy of the pointer (which is now
dangling) is dereferenced lower down in the function.
Essentially if there is a disconnect while CC_send_query_append is
running there is a risk of crash.

I hope that you can fix this soon.

Regards,
Malcolm MacLeod