Update from upstream @21551990

* Patch LevelDB to build for OSX and iOS
* Fix race condition in memtable iterator deletion.
* Other small fixes.

git-svn-id: https://leveldb.googlecode.com/svn/trunk@29 62dab493-f737-651d-591e-8d6aee1b9529

db/db_impl.h

@@ -77,10 +77,6 @@ class DBImpl : public DB {
   // Delete any unneeded files and stale in-memory entries.
   void DeleteObsoleteFiles();
 
-  // Called when an iterator over a particular version of the
-  // descriptor goes away.
-  static void Unref(void* arg1, void* arg2);
-
   // Compact the in-memory write buffer to disk.  Switches to a new
   // log-file/memtable and writes a new descriptor iff successful.
   Status CompactMemTable();