Use <dirent.h> instead of <sys/dir.h>

Using <dirent.h> and struct dirent instead of <sys/dir.h> and struct direct
is preferred and works on Android which lacks sys/dir.h.

See:
http://pubs.opengroup.org/onlinepubs/009695399/basedefs/dirent.h.html

proc/sysinfo.h

@@ -1,7 +1,7 @@
 #ifndef PROC_SYSINFO_H
 #define PROC_SYSINFO_H
 #include <sys/types.h>
-#include <sys/dir.h>
+#include <dirent.h>
 #include "procps.h"
 
 EXTERN_C_BEGIN