Add missing header files to GN files (2 of N)

third_party/leveldatabase/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//testing/test.gni")
 
 defines = [ "LEVELDB_PLATFORM_CHROMIUM=1" ]
 
 config("leveldatabase_config") {
   include_dirs = [
@@ skipping 88 matching lines @@
     "src/util/arena.cc",
     "src/util/arena.h",
     "src/util/bloom.cc",
     "src/util/cache.cc",
     "src/util/coding.cc",
     "src/util/coding.h",
     "src/util/comparator.cc",
     "src/util/crc32c.cc",
     "src/util/crc32c.h",
     "src/util/env.cc",
+    "src/util/env.h",
     "src/util/filter_policy.cc",
     "src/util/hash.cc",
     "src/util/hash.h",
     "src/util/logging.cc",
     "src/util/logging.h",
     "src/util/mutexlock.h",
     "src/util/options.cc",
     "src/util/random.h",
     "src/util/status.cc",
   ]
@@ skipping 272 matching lines @@
       ":leveldb_filename_test",
       ":leveldb_filter_block_test",
       ":leveldb_log_test",
       ":leveldb_skiplist_test",
       ":leveldb_table_test",
       ":leveldb_version_edit_test",
       ":leveldb_write_batch_test",
     ]
   }
 }