This reverts commit 629406d1.

Reason for revert: cross platform builds break.

Original change's description:
> [snapshot] include version string in the startup snapshot.
> 
> This is to easier diagnose build issues involving the snapshot.
> Sample error message for mismatching snapshot:
> 
> #
> # Fatal error in ../../src/snapshot/snapshot-common.cc, line 286
> # Version mismatch between V8 binary and snapshot.
> #   V8 binary version: 6.3.1 (candidate)
> #    Snapshot version: 6.3.0 (candidate)
> # The snapshot consists of 2820444 bytes and contains 1 contexts.
> #
> 
> 
> R=​machenbach@chromium.org
> 
> Bug: chromium:764327
> Change-Id: Icdc7aeac77819b113985b424feda814a072d5406
> Reviewed-on: https://chromium-review.googlesource.com/684295
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Yang Guo <yangguo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48161}

TBR=machenbach@chromium.org,yangguo@chromium.org

Change-Id: I35a9b575e4f7fe5c45c9dc6f9e774c3e6d30049c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:764327
Reviewed-on: https://chromium-review.googlesource.com/684315Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48162}