[cairo] Speeding up _cairo_fixed_from_double

[Daniel Amelang]

> > Anyone who's building a fat binary effectively needs to go through a
> > build twice -- including the full configure stage, once for each arch &
> > SDK.  If someone has this optimized down to just doing a single build
> > that builds both at the same time, great, but then making sure this case
> > works is on their shoulders.  With a compile-time endian check, cairo
> > will compile and run correctly when built for either the x86 or the ppc
> > architecture, and that's all that's required for universal binaries.
>
> Building twice sucks, and if you have a configure test you'll need to
> actually build on two different systems and use lipo to merge the
> binaries after the fact.

I still see this as an autotools problem (for those that see it as a
problem). It appears that what you're proposing is for the
autotools-build-based projects to all add code into their build
process to account for building fat binaries. I'm not really sold on
that idea.

Like you said, the problem is akin (if not one and the same) to
general cross-compling with autotools. It's a problem that's already
been solved using the toolset rather than getting the library
developers to special case their build process.

My opinion aside...along the line of what you're looking for (getting
autotools to manage building fat binaries), this fellow seems to have
an interesting patch to achieve that:

http://ascarter.wordpress.com/2006/05/18/sqlite-universal-binary/

Dan