kevans 3a6f347641 Only set WARNS if not defined
This would allow interested parties to do experimental runs with an
environment set appropriately to raise all the warnings throughout the
build; e.g. env WARNS=6 NO_WERROR=yes buildworld.

Not currently touching the numerous instances in ^/tools.

MFC after:	1 week
2020-09-11 13:28:37 +00:00
..
2020-09-11 13:28:37 +00:00