[WebGL] Fix WebGL build on master

[JoshEngebretson]

We have PR coverage on Windows, macOS, Linux, Android, and iOS, however WebGL currently does not, it appears I broke the build!

Here's at least the first error when compiling under Emscripten

/Users/jenkins/Home/workspace/Atomic_EditorWebPlayer/Source/Atomic/Metrics/Metrics.cpp:97:9: error: use of undeclared identifier 'snprintf'; did you mean 'vswprintf'?
        snprintf(name, NAME_MAX_LENGTH, "%-20s", metric.classname.CString());

There may be more errors, or this may be the only one, who will find out? 🎱

[ghost]

I am able to reproduce this, it appears to be a header file issue with emcc.

[JoshEngebretson]

Closed via #1347