Fix MSVC warning C4018 for sqlite.

Fix MSVC warning C4018 for sqlite.

This is a warning about signed vs. unsigned values in a comparison.  The code in
question was added entirely by a previous patch, so this simply modifies that
patch, and the results of applying it.

Adding an "(unsigned)" C-style cast is a somewhat ugly fix to one location, but
the alternative would be a potentially-vast change to the APIs in question to
change int to unsigned throughout the transitive closure of places that touch
this.  I didn't seriously investigate doing this.

BUG=398202
TEST=none

Committed: https://crrev.com/b0bf37632646237f4005203cf08e76e3b94e545c
Cr-Commit-Position: refs/heads/master@{#339765}

[Peter Kasting, 2015-07-21 18:46:50]

pkasting@chromium.org changed reviewers:
+ shess@chromium.org

[Peter Kasting, 2015-07-21 18:46:50]

Scott, I didn't see recover.c in the source tree at sqlite.org, so I assume
either you didn't send your patch upstream, or it wasn't accepted.  I'm hoping
this means I don't need to do anything upstream-related and can just send you
this patch.  Let me know if not.

Also let me know if there are better ways to fix these cases, the cast I added
in particular makes me kinda sad.

[Scott Hess - ex-Googler, 2015-07-21 21:11:42]

LGTM

I'm not sure changing nCols to int would be all that bad, but I'm also not sure
about whether it would be off-style for the rest of the code, and I'm not super
excited about mind-melding with this code again to satisfy some compiler :-).

On 2015/07/21 18:46:50, Peter Kasting wrote:
> Scott, I didn't see recover.c in the source tree at http://sqlite.org, so I
assume
> either you didn't send your patch upstream, or it wasn't accepted.  I'm hoping
> this means I don't need to do anything upstream-related and can just send you
> this patch.  Let me know if not.

It's not upstream.  I dropped them an offer to pull it in, I don't recall
getting a response, maybe I should ping again.

[Peter Kasting, 2015-07-21 21:42:00]

The CQ bit was checked by pkasting@chromium.org

[commit-bot: I haz the power, 2015-07-21 21:42:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1248763003/1

[commit-bot: I haz the power, 2015-07-21 22:28:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-21 22:29:32]

Patchset 1 (id:??) landed as
https://crrev.com/b0bf37632646237f4005203cf08e76e3b94e545c
Cr-Commit-Position: refs/heads/master@{#339765}