RE: [PATCH] Memory leak, at src/common/exec.c

According to [1], windows does not support setenv, so for the patch to work [3],  would need to add it.
With the possibility of setenv going further [2], I am submitting in this thread, the patch to add setenv support on
thewindows side, avoiding starting a new trhead. 
It is based on pre-existing functions, and seeks to correctly emulate the functioning of the POSIX setenv, but has not
yetbeen tested. 

If this work is not acceptable then it is finished. And two memory leaks and a possible access beyond heap bounds,
reportedand not fixed. 

regards,
Ranier Vilela

[1] https://www.postgresql.org/message-id/29478.1576537771%40sss.pgh.pa.us
[2] https://www.postgresql.org/message-id/30119.1576538578%40sss.pgh.pa.us
[3]
https://www.postgresql.org/message-id/SN2PR05MB264066382E2CC75E734492C8E3510%40SN2PR05MB2640.namprd05.prod.outlook.com