kes Add code to tell the OS that we no longer need a cached

     file that we were reading. In findlib/bfile.c.  Also,
     only cache files that we are reading.
kes  Tweak to bsmtp to eliminate compiler warnings on Win32.
kes  Implement script to automatically generate cats and dll .def
     files for Win32 dll.
kes  Update README.mingw32 to include new .def file generation.