Squashed 'src/leveldb/' changes from 936b461..e991315

e991315 Merge upstream LevelDB 1.15.
0cfb990 Release LevelDB 1.15
02ac9f1 Merge upstream LevelDB 1.14.
0b9a89f Release LevelDB 1.14

git-subtree-dir: src/leveldb
git-subtree-split: e991315d7fe4ca84a98902578106cbffa3dcccfd

util/testutil.h

@@ -24,7 +24,7 @@ extern std::string RandomKey(Random* rnd, int len);
 // "N*compressed_fraction" bytes and return a Slice that references
 // the generated data.
 extern Slice CompressibleString(Random* rnd, double compressed_fraction,
-                                int len, std::string* dst);
+                                size_t len, std::string* dst);
 
 // A wrapper that allows injection of errors.
 class ErrorEnv : public EnvWrapper {