[BUILDROBOT][PATCH] Fix mmix (unused variable)

[Hans-Peter Nilsson]

On Fri, 18 Jul 2014, Jan-Benedict Glaw wrote:
> This was a build using GCC's ./contrib/config-list.mk to do the build.
> It passes --enable-werror-always to top-level `configure', this is
> where the -Werror comes from.

Aha.  Looks like it's of more use than theoretical pain; sounds
like this should (effectively) be the default for *non-releases*
when cross-compiling, with the possibility to override
per-target.  Agreement?  Anyone against?  1/2 :)

It should be per-target because there *may* be port-specific
constructs warned about by buggy previous-but-not-ancient
gcc-versions, where working around the warnings would cause
unwanted obfuscation.  (IIRC gdb does something like this.)

Is that the reason it's not the default, that there are such
constructs in the non-port-specific parts?  But then that would
have already been noticed through use of the config-list.mk, no?

brgds, H-P