Add missing declaration of ino_t.

POSIX requires that <dirent.h> provides ino_t in the XSI case. In our
case, this wasn't being exposed, as d_ino is a macro that expands to
d_fileno that is an uint32_t, not an ino_t.

include/dirent.h

@@ -38,15 +38,23 @@
  * the getdirentries(2) system call.
  */
 #include <sys/cdefs.h>
+#include <sys/_types.h>
 #include <sys/dirent.h>
 
 #if __XSI_VISIBLE
+
+#ifndef _INO_T_DECLARED
+typedef	__ino_t		ino_t;
+#define	_INO_T_DECLARED
+#endif
+
 /*
  * XXX this is probably illegal in the __XSI_VISIBLE case, but brings us closer
  * to the specification.
  */
 #define	d_ino		d_fileno	/* backward and XSI compatibility */
-#endif
+
+#endif /* __XSI_VISIBLE */
 
 #if __BSD_VISIBLE