Optimise usage of videodev2.h header

opts/fourcc.c

@@ -0,0 +1,21 @@
+#include "fourcc.h"
+
+fourcc_string fourcc_to_string(unsigned format)
+{
+  fourcc_string fourcc;
+  char *ptr = fourcc.buf;
+	*ptr++ = format & 0x7F;
+	*ptr++ = (format >> 8) & 0x7F;
+	*ptr++ = (format >> 16) & 0x7F;
+	*ptr++ = (format >> 24) & 0x7F;
+	if (format & ((unsigned)1 << 31)) {
+		*ptr++ = '-';
+		*ptr++ = 'B';
+		*ptr++ = 'E';
+		*ptr++ = '\0';
+	} else {
+		*ptr++ = '\0';
+	}
+  *ptr++ = 0;
+	return fourcc;
+}