[sql] Enable disabled clang warnings.

[sql] Enable disabled clang warnings.

New version of SQLite can handle them.  I suspect probably due to
Apple support.

no-pointer-bool-conversion
no-empty-body
no-tautological-compare

BUG=none
R=thakis@chromium.org

Committed: https://crrev.com/03a5623bd68b1058603ef3b6a3c077a45d5f0ed2
Cr-Commit-Position: refs/heads/master@{#316134}

[Scott Hess - ex-Googler, 2015-02-13 00:32:50]

As long as we're in there...

[Scott Hess - ex-Googler, 2015-02-13 00:34:04]

On 2015/02/13 00:32:50, Scott Hess wrote:
> As long as we're in there...

My test methodology was to comment them out and try them.  I replicated that
-Wno-pointer-bool-conversion fired when I unpatched the indicated patch, but the
others I'm just flying blind.

[Nico, 2015-02-13 01:31:49]

lgtm, the trybots should catch any issues as we build with -Werror

(except if there's anything windows-specific, but i'll watch our clang/win bots
after this lands)

[Nico, 2015-02-13 01:31:59]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-02-13 01:33:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/921983002/1

[commit-bot: I haz the power, 2015-02-13 02:29:32]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-13 02:30:25]

Patchset 1 (id:??) landed as
https://crrev.com/03a5623bd68b1058603ef3b6a3c077a45d5f0ed2
Cr-Commit-Position: refs/heads/master@{#316134}