-Wall

Hi folks,

if you saw my today's pushes, you're aware that I only found a bug
because I used -Wall.  I fixed the bug and a few less crucial warnings.

I did NOT fix the warnings in code we took verbatim from some BSDs,
which often contain unused variables, or in some cases expressions which
are deemed to profit from extra paranthesis, e. g.

  if (a >= 0 ^ b == 0)

For that reason, I'd like to suggest to add -Wall by default to the
build flags for newlib, just as it is already for ages in the Cygwin
tree.

Anybody having a strong opinion, pro or contra?


Corinna