Rename configure.in to configure.ac.
Use uptodate dist targets.
Update configfsf.*.
Update config.* for YASM.
Treat Cygwin64 as Mingw64.
Ran "autoreconf -fi" and put back correct config.(guess|sub) files.
Fix bug in t-scan test.

Reported by Daniel R. Grayson and fixed by Leif Leonhardy.
Put back configfsf.sub trick from devel/configfsf.sub.diff.