add arch tuple matching for nt32 and nt64 in configure

the nt32 and nt64 archs will be provided by the midipix project for
building musl on top of its posix-like syscall layer for windows. at
present the needed arch files are in a separate repository, but having
the tuple matching in the upstream configure script should make it
possible to overlay the arch files without needing any further
1 file changed