[Xorg-driver-geode] proposal: always build with -march=geode

[Martin-Éric Racine]

Greetings,

Noticing Gaetan Nadon's proposed patch to prevent the building of
xf86-video-geode on non-x86 platforms, I was wondering if we should
take this approach one step further:

In addition to exiting gracefully with a warning at ./configure time
if the build host is non-x86, what if we enforced -march=geode if GCC
>= 4.3 is found (or -march=i586 if an older version is found)? In our
Geode driver's case, not only do we know which platforms to exclude,
we also know the target platform to always be -march=geode. In order
to accommodate the default compiler flags of distributions, we could
make the setting of our -march flags only be used if the -march option
is not already set.

Alternately, we could make ./configure also accept Atom and x86_64 as
suitable build hosts, in which case we'd have to enforce -march=geode
always.

Comments?
-- 
Martin-Éric