glibc before 2.17 has a bug that makes it impossible to execute binaries
that have single-byte thread-local variables:

    % node --version
    node: error while loading shared libraries: cannot allocate memory
    in static TLS block

Work around that by making the one instance in the V8 code base an int.

See: https://sourceware.org/bugzilla/show_bug.cgi?id=14898
See: https://github.com/nodesource/distributions/issues/513
See: https://github.com/nodejs/build/pull/809
Change-Id: Iefd8009100cd93e26cf8dc5dc03f2d622b423385
Reviewed-on: https://chromium-review.googlesource.com/612351
Commit-Queue: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-by: Eric Holk <eholk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47400}