Revert of GN: Use -std=gnu++0x for nacl_x86_glibc toolchain (patchset #1 id:1 of https://codereview.chromium.org/1568683002/ )
Revert of GN: Use -std=gnu++0x for nacl_x86_glibc toolchain (patchset #1 id:1 of https://codereview.chromium.org/1568683002/ )

Reason for revert:
Breaks the x64 build: crbug.com/575752

Original issue's description:
> GN: Use -std=gnu++0x for nacl_x86_glibc toolchain
>
> The nacl_x86_glibc toolchain doesn't support -std=gnu++11 or
> -std=c++11 but it does support -std=gnu++0x and -std=c++0x.
> PPAPI tests built under this toolchain (among other toolchains)
> use parts of base/ that have begun using some C++11 features that
> require -std=gnu++0x to build with nacl_x86_glibc.
>
> R=brettw@chromium.org
> BUG=none
>
> Committed: https://crrev.com/678f42a5815a53f9883807b37bd3a253e4bb9b18
> Cr-Commit-Position: refs/heads/master@{#368143}

TBR=brettw@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=575752

Review URL: https://codereview.chromium.org/1570513007

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#368413}

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