[wasm] Use a LazyInstance in wasm-linkage.cc to avoid a data race.

[wasm] Use a LazyInstance in wasm-linkage.cc to avoid a data race.

The initialization of static variables that were used originally caused
a data race because multiple threads tried to initialize the variables
at the same time. The use of a LazyInstance guarantees that the
variables get initialized exactly once.

The same problem also existed in c-linkage.cc. There I fixed the problem
by using a local variable instead of a static variable.

BUG=v8:5242
R=titzer@chromium.org

Committed: https://crrev.com/282cdf28ae13fbe6bca5cc4bd35d1f4e37372073
Cr-Commit-Position: refs/heads/master@{#38221}

[ahaas, 2016-08-01 07:24:53]

The CQ bit was checked by ahaas@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-08-01 07:24:59]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-01 07:48:27]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-01 07:48:28]

Dry run: This issue passed the CQ dry run.

[titzer, 2016-08-01 16:55:03]

lgtm

[ahaas, 2016-08-01 21:03:01]

The CQ bit was checked by ahaas@chromium.org

[commit-bot: I haz the power, 2016-08-01 21:03:07]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-01 21:04:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-01 21:06:24]

Description was changed from

==========
[wasm] Use a LazyInstance in wasm-linkage.cc to avoid a data race.

The initialization of static variables that were used originally caused
a data race because multiple threads tried to initialize the variables
at the same time. The use of a LazyInstance guarantees that the
variables get initialized exactly once.

The same problem also existed in c-linkage.cc. There I fixed the problem
by using a local variable instead of a static variable.

BUG=v8:5242
R=titzer@chromium.org
==========

to

==========
[wasm] Use a LazyInstance in wasm-linkage.cc to avoid a data race.

The initialization of static variables that were used originally caused
a data race because multiple threads tried to initialize the variables
at the same time. The use of a LazyInstance guarantees that the
variables get initialized exactly once.

The same problem also existed in c-linkage.cc. There I fixed the problem
by using a local variable instead of a static variable.

BUG=v8:5242
R=titzer@chromium.org

Committed: https://crrev.com/282cdf28ae13fbe6bca5cc4bd35d1f4e37372073
Cr-Commit-Position: refs/heads/master@{#38221}
==========

[commit-bot: I haz the power, 2016-08-01 21:06:25]

Patchset 1 (id:??) landed as
https://crrev.com/282cdf28ae13fbe6bca5cc4bd35d1f4e37372073
Cr-Commit-Position: refs/heads/master@{#38221}