Make v8 compile on VS2013.

Make v8 compile on VS2013.

VS2013 contains a number of improvements, most notably the addition of all C99 math functions.

I'm a little bit concerned about the change I had to make in cpu-profiler.cc, but I spent quite a bit of time looking at it and was unable to figure out any rational explanation for the warning.  It's possible it's spurious.  Since it seems like a useful warning in general though, I chose not to disable globally at the gyp level.

I do think someone with expertise here should probably try to determine if this is a legitimate warning.

BUG=288948
R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/23449035

Patch from Zach Turner <zturner@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16775 ce2b1a6d-e550-0410-aec6-3dcde31c8c00