Build tests for all CMake platforms on CI

[ccawley2011]

This is currently a draft because some tests aren't building properly with Emscripten and I'm not sure how to fix it.

Includes changes from #5635 and #5636. See also issue #5634.

[madebr]

FYI, I"m also having an issue with building an emscripten test application in #5727

error: undefined symbol: emscripten_sync_run_in_main_runtime_thread_

I disabled building an emscripten application in the aforementioned pr.

[slouken]

Let's go ahead and disable the emscritpen test, and enter an issue to take care of that later.

@ccawley2011, go ahead and make the replacement of the clock functions the default path, without any Vita checks.

[ccawley2011]

@ccawley2011, go ahead and make the replacement of the clock functions the default path, without any Vita checks.

OK, done.