Fix max identifier length stuff.

CC_get_max_idlen function didn't work correctly. It sent the "show
identifier_length" query to the backend, but assumed that the value comes
back in the command tag. It doesnt; the command tag is always "SHOW".

We fell back to the compiled in NAMEDATALEN_V73 default. But that's
off-by-one; the actual max identifier length is NAMEDATALEN - 1.
Minor code simplification.

Any compiler worth its salt will turn "strlen(constant)" into a constant,
so let's get rid of the fancy logic to precalculate those.
Remove option to disable geqo.

You can use the generic ConnSettings option for that.
Remove dead code
Change *ANSI* in the title of 32-bit Unicode driver setup dialog to *Unicode*.
Avoid conflicts of external symbols other than ODBC APis.
Remove *Disallow Premature* option. Use *Server Side prepare* option instead.
The option was for 7.1-7.3 servers.