Fix error reporting of connect_timeout in libpq for value parsing
The logic was correctly detecting a parsing failure, but the parsing
error did not get reported back to the client properly.
Reported-by: Ed Morley
Author: Lars Kanis
Reviewed-by: Michael Paquier
Discussion: https://postgr.es/m/
a9b4cbd7-4ecb-06b2-ebd7-
1739bbff3217@greiz-reinsdorf.de
Backpatch-through: 12