Fix compile error with Windows clang.

Fix compile error with Windows clang.

This change fixes the following errors shown during compile with Windows clang:
error: cannot pass non-trivial object of type 'ATL::CComBSTR' to variadic function; expected type from format string was 'wchar_t *' [-Wnon-pod-varargs]

BUG=https://code.google.com/p/google-breakpad/issues/detail?id=662

[Yoshisato Yanagisawa, 2015-07-29 02:01:16]

yyanagisawa@chromium.org changed reviewers:
+ thakis@chromium.org, wfh@chromium.org

[Yoshisato Yanagisawa, 2015-07-29 02:01:16]

Hi,

Let me send change list to fix Windows clang compile error.
I will send another change to fix the warnings suggested by Nico after this
change.

Thank you.

[Yoshisato Yanagisawa, 2015-07-29 02:02:59]

Note that when I tried to follow
https://code.google.com/p/google-breakpad/source/browse/trunk/README 

However, I got 500 Server error with accessing http://breakpad.appspot.com on
Step 5.

[Yoshisato Yanagisawa, 2015-08-19 03:33:36]

Do you see some problems with this change?

[Will Harris, 2015-08-19 03:35:22]

On 2015/08/19 03:33:36, Yoshisato Yanagisawa wrote:
> Do you see some problems with this change?

Sorry this keeps slipping off my radar, I will commit this to breakpad tomorrow.

[Yoshisato Yanagisawa, 2015-08-19 03:39:47]

thanks.

[Mark Mentovai, 2015-08-19 22:24:55]

mark@chromium.org changed reviewers:
+ mark@chromium.org

[Mark Mentovai, 2015-08-19 22:24:55]

LGTM

[Will Harris, 2015-08-19 22:28:52]

On 2015/08/19 22:24:55, Mark Mentovai - out til August wrote:
> LGTM

committed in https://codereview.chromium.org/1307463003/

[Yoshisato Yanagisawa, 2015-08-27 03:00:25]

I noticed that this change may cause dump_syms crash in Win32. (I am not sure
why I do not see the issue on Win64).
I am fixing.