Fix endian.h include for FreeBSD

Author: AMDmi3

src/cguittfont/irrUString.h

@@ -47,6 +47,8 @@
 #define __BIG_ENDIAN 1
 #elif __MACH__
 #include <machine/endian.h>
+#elif defined(__FreeBSD__)
+#include <sys/endian.h>
 #else
 #include <endian.h>
 #endif