general flag passing

[Benjamin Kosnik]

Hey Phil.


> It's been a while; is this still a desired change?  I have a patch here
> that will do this, except for the libgcc rebuilding.  General flags will
> be passed down and appear in src/Makefile's AC_CXXFLAGS.

Yes, I'd like to have this mechanism in place. This was a useful bit
of configuration hackery to have in place before -fhonor-std was
"fixed" in the compiler. It would be nice to have this mechanism
updated for the current build environment.


>The help output is
>
>  --enable-cxx-flags=FLAGS      pass compiler FLAGS when building library;
>                                [default=-fhonor-std]

No, don't send -fhonor-std by default. Assume this is already on, and
that --enable-libstdcxx-v3 is being passed. 

> Now, what should the default flags be, if anything?

Nothing, for the time being please.

-benjamin