In ext/odbc/php_odbc.c: odbc_sqlconnect(), only Openlink
and Empress can make use of the SQLDriverConnect function.

UnixODBC can use SQLDriverConnect as well, and in the case
of some Easysoft ODBC connections, it *must* be able to use
the SQLDriverConnect format in order to actually connect to
the database.

I have tried changing the 
  #ifdef HAVE_EMPRESS
to
  #if defined(HAVE_EMPRESS) || defined(HAVE_UNIXODBC)
and everything worked fine, giving full access to the
SQLDriverConnect method of calling odbc_connect and
odbc_pconnect.  If this could be incorporated into a later
release, it would be very useful.

(BTW, this was tested with UnixODBC 2.0.5)