Added a check for poll.h.

diff --git a/dlls/winmm/wineoss/dscapture.c b/dlls/winmm/wineoss/dscapture.c
index b2de9b4..a1c695e 100644
--- a/dlls/winmm/wineoss/dscapture.c
+++ b/dlls/winmm/wineoss/dscapture.c
@@ -36,6 +36,9 @@
 #ifdef HAVE_SYS_MMAN_H
 # include <sys/mman.h>
 #endif
+#ifdef HAVE_POLL_H
+#include <poll.h>
+#endif
 #ifdef HAVE_SYS_POLL_H
 # include <sys/poll.h>
 #endif