INSTALL.W32: document trouble with symlinks under MSYS.

   required. Run the installers and do whatever magic they say it takes

   to start MSYS bash shell with GNU tools on its PATH.

   N.B. Since source tar-ball can contain symbolic links, it's essential

   that you use accompanying MSYS tar to unpack the source. It will

   either handle them in one way or another or fail to extract them,

   which does the trick too. Latter means that you may safely ignore all

   "cannot create symlink" messages, as they will be "re-created" at

   configure stage by copying corresponding files. Alternative programs

   were observed to create empty files instead, which results in build

   failure.

 * Compile OpenSSL:

   $ ./config