avcodec/crystalhd: Add #if HAVE_UNISTD_H around #include <unistd.h>

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/crystalhd.c

@@ -77,7 +77,6 @@
 #include <inttypes.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 
 #include <libcrystalhd/bc_dts_types.h>
 #include <libcrystalhd/bc_dts_defs.h>
@@ -90,6 +89,10 @@
 #include "libavutil/intreadwrite.h"
 #include "libavutil/opt.h"
 
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 /** Timeout parameter passed to DtsProcOutput() in us */
 #define OUTPUT_PROC_TIMEOUT 50
 /** Step between fake timestamps passed to hardware in units of 100ns */