ecpg: Catch zero-length Unicode identifiers correctly
The previous code to detect a zero-length identifier when using
Unicode identifiers such as
exec sql select u&"";
did not work. This fixes that.
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/
82fafa79-331c-9d65-e51b-
8b5d1b2383fc%40enterprisedb.com