[win32] Improve random mmap address generation on 64-bit.

[win32] Improve random mmap address generation on 64-bit.

Currently we only generate addresses in the range 2GiB to 4GiB, because
of a bug, when running in 64-bit mode. With this fix we now use the full
range 2GiB to 4096GiB.

BUG=v8:3997
LOG=n
R=svenpanne@chromium.org

Committed: https://crrev.com/ee73c6f3e756ec2e67ee721761a53f60c3d544d8
Cr-Commit-Position: refs/heads/master@{#27610}

[Benedikt Meurer, 2015-04-07 06:17:51]

Hey Sven,

Following your suggestions, this should fix the issue. Please take a look.

Thanks,
Benedikt

[Sven Panne, 2015-04-07 06:38:20]

lgtm

[Benedikt Meurer, 2015-04-07 07:11:39]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-04-07 07:11:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1051303003/1

[commit-bot: I haz the power, 2015-04-07 07:13:57]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-07 07:14:13]

Patchset 1 (id:??) landed as
https://crrev.com/ee73c6f3e756ec2e67ee721761a53f60c3d544d8
Cr-Commit-Position: refs/heads/master@{#27610}