Default-enable external startup data for Linux for stand-alone builds.

Default-enable external startup data for Linux for stand-alone builds.

Notes:
- Other platforms to follow later.
- This follows Chromium practice, that mostly uses this feature these days.
- The statically linked-in startup data will stay. So whoever prefers
  the old way just needs to set the flag differently.

BUG=

Committed: https://crrev.com/6d0dcaabe55ca3556bebfd771fbc7fd560fdd4e0
Cr-Commit-Position: refs/heads/master@{#26884}

[vogelheim, 2015-02-25 17:34:09]

vogelheim@chromium.org changed reviewers:
+ machenbach@chromium.org

[Michael Achenbach, 2015-02-26 14:02:30]

lgtm

[vogelheim, 2015-02-26 14:10:12]

The CQ bit was checked by vogelheim@chromium.org

[commit-bot: I haz the power, 2015-02-26 14:10:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/959693002/1

[commit-bot: I haz the power, 2015-02-26 14:55:22]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-26 14:55:33]

Patchset 1 (id:??) landed as
https://crrev.com/6d0dcaabe55ca3556bebfd771fbc7fd560fdd4e0
Cr-Commit-Position: refs/heads/master@{#26884}

[vogelheim, 2015-02-26 15:09:22]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/962593003/ by vogelheim@chromium.org.

The reason for reverting is: Breaks "Simple Leaks Check".

[vogelheim, 2015-02-26 15:48:41]

Patchset #2 (id:20001) has been deleted