BUG #17186: In connect.c, the lock connections_mutex is not correctly released(Line 463) at the return(Line 522)

The following bug has been logged on the website:

Bug reference:      17186
Logged by:          An improper locking bug due to the unreleased lock connections_mutex in
/ecpg/ecpglib/connect.c
Email address:      ryancaicse@gmail.com
PostgreSQL version: 14beta3
Operating system:   All
Description:        

This is a possible improper locking bug, which can lead to resource leaks
and even deadlock. I am not sure whether it can lead to a security
problem.
The problem is that the lock connections_mutex should be released at the end
of the function. But it not released when conn_keywords == NULL ||
conn_values == NULL (ecpg_alloc got errors and return NULL).
Thank you for your checking.

Locations:
https://github.com/postgres/postgres/blob/c30f54ad732ca5c8762bb68bbe0f51de9137dd72/src/interfaces/ecpg/ecpglib/connect.c#L463
https://github.com/postgres/postgres/blob/c30f54ad732ca5c8762bb68bbe0f51de9137dd72/src/interfaces/ecpg/ecpglib/connect.c#L522