Roll to GCC 4.9

Picked changes from branch svn-mirror/google/gcc-4_9-mobile at
  commit 1a85936bfe3d34d9a8aa8f435d19ce326c6cc088

This also includes the changes for the cortex-a53 erratum 835769

BUG=chromium:423463
    chromium:433095
TEST=Lots of testing including
     - Unit
     - hwtests
     - Kernel
     - Firmware
     - Performance
     See: https://goto.google.com/gcc_49_testing
CQ-DEPEND=CL:218260

Change-Id: Icccc71b6225106b132519246db711327f3ab312e
Reviewed-on: https://chromium-review.googlesource.com/217962
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Caroline Tice <cmtice@chromium.org>
Commit-Queue: Luis Lozano <llozano@chromium.org>
Tested-by: Luis Lozano <llozano@chromium.org>
20835 files changed