Instructions from Jared Davis for building ACL2 on Windows using mingw

We thank Jared Davis for providing the following instructions for ACL2 Version 2.8, which we include verbatim and expect to apply to future versions, except that the certify-books target for `make' below should be replaced by basic.
	      Building ACL2 on Windows from Scratch

   Note: The disk space requirements are large.  Not including
   emacs, I had about 275 MB taken up by msys/mingw32/gcl/acl2
   during the build process.  You can probably use much less
   space by removing files after you use them, but I didn't
   bother to do that.

   Here are the steps I took:

   Downloaded emacs 21.3 full distribution and installed
   Downloaded msys 1.10.10, installed to c:\acl2
   Downloaded mingw 3.1.0-1, installed to c:\acl2\mingw
   Downloaded gcl 2.5.3, extracted to c:\acl2\mingw
   Downloaded acl2 2.8, extracted to c:\acl2\sources

   Compiling gcl:

     in msys:

       cd /acl2/ming2/gcl-2.5.3
       make install

   Compiling acl2:

     copy "etags.exe" to /mingw/bin.  you can find this program
     in your emacs folder, under "bin".

     in msys:

       cd /sources

   Certifying ACL2 books:
   This took 111 minutes on my Athlon 2500+

     in msys:

       cd /sources

       mv nsaved_acl2.gcl.exe saved_acl2.exe

       vim books/Makefile-generic, remove "nice" from this line:
	   ACL2=time nice ../../saved_acl2

       make certify-books ACL2=/sources/saved_acl2.exe