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/log_test.cc

@@ -76,7 +76,7 @@ class LogTest {
       return Status::OK();
     }
 
-    virtual Status Skip(size_t n) {
+    virtual Status Skip(uint64_t n) {
       if (n > contents_.size()) {
         contents_.clear();
         return Status::NotFound("in-memory file skipepd past end");