include/unistd.h: merged

Also removing lseek64, pread64, pwrite64.

Those functions have lost their "raison d'être", when off_t switched to
64bits.

Change-Id: I5aea35f01d6d10e3d6578a70323da7be5eca315a

commands/sprofdiff/sprofdiff.c

@@ -5,6 +5,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <minix/type.h>
 
 #include "tdist.h"