Switching compilers (was: PKG_SKIP/FAIL_REASON)

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

> C) Have something like the within-family compiler choice, but extend it
>    to across families, so that even if configured to build with clang a
>    package marked as not working with clang would get built with gcc.
I guess the tricky part is libtool. You either need a matching libtool 
for each compiler (family) and install the correct one before building 
or you need to add --tag arguments to libtool invocations calling a 
compiler.