new buildfarm with gcc & clang "trunk" -Werror?

Dear devs,

I've been running buildfarm members moonjelly and seawasp which use gcc &
clang weekly recompiled trunk versions to build postgres branch HEAD for
about 6 months

These helped uncover bugs in both gcc & clang, which were reported and
fixed, so there is a benefit on this side.

These compilations currently fail with -Werror. "gcc trunk" generates 44
warnings about snprintf-related possible truncations, anc "clang trunk"
generates 68 warnings about undeclared strl* functions.

Would the project feel appropriate to:

- fix these warnings (other than putting -Wno-format-truncation or
similar workarounds...).

- add permanent gcc/clang trunk beasts with -Werror
(if so, I'd suggest cannonball & seanettle for the names).

The rational is that postgres will need to be compilable with future
versions of these compilers, eventually, so the earlier issues are
detected the better. Also, warnings help detect latent bugs.

However these beasts would be more unstable than others, eg start failing
when a new warning is added. They are somehow already unstable though, as
every few month postgres compilation would fail because of a new bug in
the compilers.

--
Fabien.