roll clang 198389:202554

roll clang 198389:202554

This change contains several big changes, many of the caused by upstream
llvm enabling c++11 in their codebase and thus having higher minimum
requirements for their toolchain and runtime environment:

* clang on OS X now requires libc++, which means it'll only run on OS X 10.7+,
  so change the deployment target from 10.5 to 10.7 (we were planning on
  requiring 10.8 or 10.9, see bug 335325, but since several people are waiting
  on a new clang, let's go to 10.7 only for now and do more as a follow-up)
* On OS X, the compiler is only usable with libc++ if libc++ is checked out
  and `make install` is run, so do that for the phase 1 compiler.
  (Chrome doesn't use libc++ yet, so we don't do that for the bootstrapped
  compiler.)
* clang on linux now needs libstdc++ 4.7+ which isn't present on precise.
  So we now include a newer libstdc++ in the compiler bundle (meaning
  this clang should still run on precise).
* clang is broken for android at r202554. To unblock oilpan, merge three
  later changes into this roll, llvm r202793, r203601, and r203635

Regular, less tricky clang roll stuff:
* Disable the new warning -Wabsolute-value for now (crbug.com/351479
  for turning it on)
* Disable -Wno-tautological-pointer-compare for libxml where it now
  fires.
* Since this bundles a new version of the oilpan plugin, bump its suffix to _3
* Change plugin code to track upstream api change
* Remove plugin flag check-url-directory as that's now always on

Due to the c++11 stuff, it's likely that this change will get reverted a few times.

BUG=351479, 287029, 341352, 333968, 335325
TBR=hans@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257618

[Nico, 2014-03-18 00:44:57]

The CQ bit was checked by thakis@chromium.org

[Nico, 2014-03-18 00:45:49]

nacl roll went in at r257490

[commit-bot: I haz the power, 2014-03-18 00:48:26]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/thakis@chromium.org/195623002/370001

[commit-bot: I haz the power, 2014-03-18 01:18:44]

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

[commit-bot: I haz the power, 2014-03-18 01:18:45]

Retried try job too often on chromium_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=chromium_p...

[Nico, 2014-03-18 10:53:29]

Committed patchset #21 manually as r257618 (tree was closed).

[tfarina, 2014-03-18 13:36:40]

https://codereview.chromium.org/195623002/diff/370001/tools/clang/scripts/plu...
File tools/clang/scripts/plugin_flags.sh (left):

https://codereview.chromium.org/195623002/diff/370001/tools/clang/scripts/plu...
tools/clang/scripts/plugin_flags.sh:22: -Xclang check-url-directory
So I added it in - https://codereview.chromium.org/183763018, removed from
tools/clang/plugins in - https://codereview.chromium.org/185543003, and when you
roll you remove from plugin_flags.sh.

OK, I'm understanding this process better.