xp: copy dbghelp.dll to output dir and have base.isolate use it there

xp: copy dbghelp.dll to output dir and have base.isolate use it there

Previous CL https://codereview.chromium.org/943933005 didn't work properly
because the dll wasn't in the same directory as the binary, so it was still
loading the system dbghelp.dll. See details in 460506.

Copies dbghelp.dll to the output dir, and has the isolate file point at that.

Re-enable tests that were failing due to dbghelp hanging.

XP test run here: https://chromium-swarm.appspot.com/user/task/25d5bc17b6dddc10

BUG=460506, 461160
Committed: https://crrev.com/09acc50cfadc6aa38db23ddadec134410ec968c0
Cr-Commit-Position: refs/heads/master@{#317868}

Committed: https://crrev.com/f063a7eb8a746bc2479509664d26e193e35b6957
Cr-Commit-Position: refs/heads/master@{#317926}

[scottmg, 2015-02-24 18:44:38]

scottmg@chromium.org changed reviewers:
+ cpu@chromium.org

[cpu_(ooo_6.6-7.5), 2015-02-24 18:57:36]

lgtm

[scottmg, 2015-02-24 19:02:26]

The CQ bit was checked by scottmg@chromium.org

[commit-bot: I haz the power, 2015-02-24 19:03:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/951083003/100001

[commit-bot: I haz the power, 2015-02-24 20:18:36]

Committed patchset #6 (id:100001)

[commit-bot: I haz the power, 2015-02-24 20:20:03]

Patchset 6 (id:??) landed as
https://crrev.com/09acc50cfadc6aa38db23ddadec134410ec968c0
Cr-Commit-Position: refs/heads/master@{#317868}

[scottmg, 2015-02-24 22:21:12]

A revert of this CL (patchset #6 id:100001) has been created in
https://codereview.chromium.org/954003002/ by scottmg@chromium.org.

The reason for reverting is: some blink waterfall failing for reasons unclear.
dependency on base.isolate without depending on base maybe?.

[scottmg, 2015-02-24 22:46:18]

Reverted, and relanding -- I put the dll copy in 'base_unittests', not 'base',
so it succeeded on the trybots here, but failed on all future trybots if they
didn't touch base_unittests. :(

[scottmg, 2015-02-24 22:47:04]

Diff from 6->7 is the change for reland, going to add a rebase as ps8+.

[scottmg, 2015-02-24 23:29:19]

The CQ bit was checked by scottmg@chromium.org

[scottmg, 2015-02-24 23:29:19]

The patchset sent to the CQ was uploaded after l-g-t-m from cpu@chromium.org
Link to the patchset: https://codereview.chromium.org/951083003/#ps140001
(title: "rebase")

[commit-bot: I haz the power, 2015-02-24 23:30:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/951083003/140001

[commit-bot: I haz the power, 2015-02-25 00:17:42]

Committed patchset #8 (id:140001)

[commit-bot: I haz the power, 2015-02-25 00:20:02]

Patchset 8 (id:??) landed as
https://crrev.com/f063a7eb8a746bc2479509664d26e193e35b6957
Cr-Commit-Position: refs/heads/master@{#317926}