Description:
------------
sha1_file() not releasing memory.

After calling thousands of sha1_file() I noticed that memory resources are not being freed. Script evenually bombs due to lack of resources.

** Note ** I think md5_file() is doing the same thing.

Reproduce code:
---------------
function getFiles(&$rdi,$depth=0) {

   if (!is_object($rdi))
       return;
     
   for ($rdi->rewind();$rdi->valid();$rdi->next()) {
     
       if ($rdi->isDot())
           continue;
     
       if ($rdi->isDir() || $rdi->isFile()) {
     
           if($rdi->isFile()
               echo sha1_file($rdi->current());
     
           if ($rdi->hasChildren())
               getFiles($rdi->getChildren(),1+$depth);
       }
   }
}

//** I figured that calling clearstatcache() might help, but no, it didn't **//