Roll src/third_party/leveldatabase/src/ 6fa456667..d177a0263 (9 commits)

https://chromium.googlesource.com/external/leveldb.git/+log/6fa45666703a..d177a0263cce

$ git log 6fa456667..d177a0263 --date=short --no-merges --format='%ad %ae %s'
2018-04-17 costan Replace port_posix with port_stdcxx.
2018-04-16 falke.marco Fix sign mismatch warnings in GCC.
2018-04-13 costan Add forgotten <limits> header to util/logging.cc.
2018-04-13 costan Reimplement ConsumeDecimalNumber.
2018-04-13 costan Add tests for ConsumeDecimalNumber.
2018-04-11 costan Document the building process.
2018-04-10 costan Replace NULL with nullptr in C++ files.
2018-04-10 costan Remove PLATFORM_IS_LITTLE_ENDIAN from port/posix.h.
2018-04-09 costan Define LEVELDB_HAS_PORT_CONFIG_H for old compilers.

Created with:
  roll-dep src/third_party/leveldatabase/src

Change-Id: Icabf330020abf70e91b00c835d34af070bcea4e2
Reviewed-on: https://chromium-review.googlesource.com/1015774Reviewed-by: Chris Mumford <cmumford@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552445}

DEPS

@@ -692,7 +692,7 @@ deps = {
   },
 
   'src/third_party/leveldatabase/src':
-    Var('chromium_git') + '/external/leveldb.git' + '@' + '6fa45666703add49f77652b2eadd874d49aedaf6',
+    Var('chromium_git') + '/external/leveldb.git' + '@' + 'd177a0263cce4344d05188521ad53459c369b940',
 
   'src/third_party/libFuzzer/src':
     Var('chromium_git') + '/chromium/llvm-project/compiler-rt/lib/fuzzer.git' + '@' +  Var('libfuzzer_revision'),