Roll to GCC 4.9.2 (Retry)

    Picked changes from branch svn-mirror/google/gcc-4_9-mobile at
      commit 952223c94dee89f9c4e6b39fa752627cf1af8936

BUG=chromium:460557
TEST=cbuildbots: chromiumos-sdk, several boards for each platform.
     hwtest and some kernel testing.
     Tested on projects that had issues with previous roll:
       Flash, chromoting, chromecast, breakpad
     Verified performance (small improvements on ARM).

Change-Id: Ie79a45b21f92000dca07e34e849c0cf4cbc6761a
Reviewed-on: https://chromium-review.googlesource.com/255781
Reviewed-by: Caroline Tice <[email protected]>
Reviewed-by: Mike Frysinger <[email protected]>
Tested-by: Luis Lozano <[email protected]>
741 files changed