When crosscompiling, does configure really need --build?

[Dan Kegel]

I've noticed lately that I need to specify --build when configuring
software for cross-compilation.  This is a big burden, because
I write portable build scripts that invoke configure, make, etc.

It seems somewhat absurd, but the best way I can figure to find out
what to pass to --build is to run a second layer of autoconf
on my build script.

Please, someone tell me I don't really need to specify --build...
- Dan