Buffer access() calls.

One of the remaining >1000-calls-hot syscalls on FF startup, and simple to wrap.  New top 10 is
<pre>
syscall	count
-------	-----
   5	  3932  (open from within libc itself)
 240	  3443  (futex)
 102	  2480  (socketcall)
 168	  1657  (poll)
   6	   926  (close from within libc)
 220	   912  (getdents64)
 192	   884  (mmap2)
  85	   766  (readlink)
 195	   750  (stat64, presumably from within libc itself)
 140	   714  (_llseek)
</pre>