[RFA v2] Make it easy to make --disable-werror the default for both binutils and gdb

[Joel Brobecker]

Thanks, Alan and Tom.

I just pushed the patch to master.

Regarding the "-a" vs "&&", I am happy making the change, if you would
like me to. It seems from the text quoted by Maciej that "&&" might
be more portable, but since we've been using "-a" without issue (to
my knowledge) I am tempted to wait until a portability issue actually
shows up. The workaround in case of problem is fairly easy - use
another shell like bash, for instance.

-- 
Joel