tcmalloc: use standard-conforming alignof in debugallocation.cc

Copy recent fix from upstream gperftools:

- https://github.com/gperftools/gperftools/commit/c41688bf20186723367b560ceb539b2330951ddb

  Use standard-conforming alignof in debugallocation.cc

  Clang was giving warning that alignof(<variable>) is extension. So
  we're now doing alignof of decltype.

BUG=724399,b:70905156

Change-Id: I6d728515dbff8b4f130c0e602a150de67b2ad1ba
Reviewed-on: https://chromium-review.googlesource.com/1189130
Commit-Queue: Gabriel Marin <gmx@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#586447}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 9ac16e67c221a1123fd3b867aa16cffdfd510de4
1 file changed
tree: 7269bf57192d8c11a1733cb52c21519c90e4c486
  1. src/