10l to Benoit, poll.h is already included below, and this broke compilation on mingw

Originally committed as revision 9620 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffserver.c

@@ -25,7 +25,6 @@
 #endif
 #include <string.h>
 #include <stdlib.h>
-#include <sys/poll.h>
 #include "avformat.h"
 
 #include <stdarg.h>