Add a header file with the function prototype to address this issue.
This has the positive side effect of fixing a couple of implicit
declaration warnings.
The problem was originally reported as Debian bug 447278.
patch by Dann Frazier and Andrea Mennucci, mennucc1 debian org
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@24824 b3059339-0415-0410-9bf9-f77b7e298cf2
