updated Mingw32 instructions.

 * Compiler installation:

   Mingw32 is available from <ftp://ftp.xraylith.wisc.edu/pub/khan/

   gnu-win32/mingw32/gcc-2.95.2/gcc-2.95.2-msvcrt.exe>. GNU make is at

   <ftp://agnes.dida.physik.uni-essen.de/home/janjaap/mingw32/binaries/

   make-3.76.1.zip>. Install both of them in C:\egcs-1.1.2 and run

   C:\egcs-1.1.2\mingw32.bat to set the PATH.

   gnu-win32/mingw32/gcc-2.95.2/gcc-2.95.2-msvcrt.exe>. Extract it

   to a directory such as C:\gcc-2.95.2 and add c:\gcc-2.95.2\bin to

   the PATH environment variable in "System Properties"; or edit and

   run C:\gcc-2.95.2\mingw32.bat to set the PATH.

 * Compile OpenSSL: