cache problem

[Duft Markus]

Hi!

I just noticed, that when i enable a config.cache that is used by more
than one package is problematic, when the first on checks for the build
system type only, and the second for both build and host system type.
This is, because the host system type check uses ac_cv_build_alias,
which is set only if build system type (ac_cv_build) is not cached.

Now the first package caches the build system type, but not the host
system type, and the second package cannot configure, since the call to
config.sub misses an argument (since ac_cv_build_alias is used, which is
empty, since build system type was cached)...

Hope I made myself clear :) excuse my English...

Cheers, Markus