Patch for jdbc ResultSet.getTimestamp()

Included is a patch that fixes a bug introduced in the lastest version
(1.22) of interfaces/jdbc/org/postgresql/jdbc2/ResultSet.java. That
change removed a line that set the variable s to the value of the
stringbuffer. This fix changes the following if checks to check the
length of the stringbuffer instead of s, since s no longer contains the
string the if conditions are expecting.

The bug manifests itself in getTimestamp() loosing the timezone
information of timestamps selected from the database, thereby causing
the time to be incorrect.

If possible this patch should be patched into 7.1 for the upcoming 7.1.2
patch.

thanks,
--Barry