Fix Coverity ID 1215458 Uninitialized pointer field

git-svn-id: svn://svn.icculus.org/fs2open@10715 387891d4-d844-0410-90c0-e4c51a9137d3
Fix Coverity ID 1215457 Out-of-bounds write

git-svn-id: svn://svn.icculus.org/fs2open@10716 387891d4-d844-0410-90c0-e4c51a9137d3