Fixed bug dereferencing garbage, causing crash.

Fixed bug dereferencing garbage, causing crash.

Commit fa8be4a3fc5d81e9ec1f6c218fcf55c95d34fd10 included code to free the
resultDetails of the gameInfo structure.  That exact code exists a few lines
above where it was added.  None of these free() calls finish by setting the
member to NULL afterword, therefore repeated attempts to test/free() the
members result in an attempt to free() memory winboard no longer owns, and
an eventual crash.

link to problematic commit: http://git.savannah.gnu.org/cgit/xboard.git/commit/?id=fa8be4a3fc5d81e9ec1f6c218fcf55c95d34fd10