Don't #define snprintf in VS 2015 builds.

Don't #define snprintf in VS 2015 builds.

The function snprintf is not available in Visual Studio prior to VS
2015. In some places this omission is dealt with with a #define to map
snprintf to _snprintf. This was never a good idea (_snprintf doesn't
guarantee null-termination) and with VS 2015 it is not even legal.

This change conditionally disables one instance of this remapping.

The build errors that occur without this change are:

stdio.h(1926): warning C4005: 'snprintf': macro redefinition
stdio.h(1926): note: command-line arguments:  see previous
definition of 'snprintf'
stdio.h(1929): fatal error C1189: #error:  Macro definition of
snprintf conflicts with Standard Library function declaration

R=scottmg@chromium.org
BUG=440500
Committed: https://crrev.com/2622e27d880e88b21d8eceb98b6863cdf6dc9afd
Cr-Commit-Position: refs/heads/master@{#324157}

[brucedawson, 2015-04-07 20:22:14]

brucedawson@chromium.org changed reviewers:
+ scottmg@chromium.org

[brucedawson, 2015-04-07 20:22:35]

Working through blocking issues...

[brucedawson, 2015-04-07 20:47:10]

brucedawson@chromium.org changed reviewers:
+ vandebo@chromium.org

[brucedawson, 2015-04-07 20:47:10]

Scott, can you verify the .gyp/VS goodness of this?

vandebo@ can you okay the libexif aspect of this?

I believe this gets all the snprintf-defined-on-command-line errors now.

[vandebo (ex-Chrome), 2015-04-07 20:49:26]

vandebo@chromium.org changed reviewers:
+ thestig@chromium.org
- vandebo@chromium.org

[vandebo (ex-Chrome), 2015-04-07 20:50:04]

-> thestig@

[scottmg, 2015-04-07 21:23:13]

lgtm

[Lei Zhang, 2015-04-07 21:38:17]

lgtm

[brucedawson, 2015-04-07 21:43:01]

The CQ bit was checked by brucedawson@chromium.org

[commit-bot: I haz the power, 2015-04-07 21:44:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1069433002/20001

[commit-bot: I haz the power, 2015-04-08 00:14:17]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-08 00:15:15]

Patchset 2 (id:??) landed as
https://crrev.com/2622e27d880e88b21d8eceb98b6863cdf6dc9afd
Cr-Commit-Position: refs/heads/master@{#324157}