videosoftware: Added hack to bypass xfb just so fifoplayer works.

Fifoplayer depends on the old behaviour of videosoftware (and the other
hardware backends in non virtual/real xfb modes) where the framebuffer
gets rendered directly to the screen.

Really fifoplayer should call BeginFrame/EndFrame when it finished
rendering a frame, but adding this hack back in is simpler.
videosoftware: Provide a more elaborate comment on the FifoPlayer support hack.
CMake: detect GTest if it is installed
Remove another clamp function laying in the codebase and replace it with the one in MathUtil.h.
Merge pull request #121 from lioncash/remove-clamp

Remove another clamp function laying in the codebase and replace it with the one in MathUtil.h.
Add the infrastructure required to easily add unit tests and test it with a very simple test file.
Tests: Add more MMIO tests as an example.
Fix a case where the wrong placeholders were being assigned for the up and down D-Pad buttons in the TAS dialog.
Merge pull request #123 from lioncash/tas-bugfix

Fix a case where the wrong placeholders were being assigned for the up and down D-Pad buttons in the TAS dialog.
Merge pull request #119 from delroth/unittests

Add support for GTest based UnitTests
Do not hard fail when running 'make unittests' without GTest.
Merge pull request #124 from delroth/master

Do not hard fail when running 'make unittests' without GTest.
Unittests: Always use GTest from Externals (recommended way from GTest FAQ).
Merge pull request #125 from delroth/master

Unittests: Always use GTest from Externals (recommended way from GTest FAQ).
UnitTests: ensure the Binaries/Tests directory exists before linking.
Merge pull request #126 from delroth/master

UnitTests: ensure the Binaries/Tests directory exists before linking.
Make the base calculation in CheatsWindow simpler.

First and foremost this should test the checked state, not its direct value.
This should never have used multiplication at all. Seriously, what the hell?

The only values it would have given is true or false, so the only cases are 0*6 and 1*6.
Merge pull request #127 from lioncash/cheat-dlg-simplification

Make the base calculation in CheatsWindow simpler.
Change the DebugInterface, PPCDebugInterface, and DSPDebugInterface to use CamelCase names.

This is the standard coding convention in the codebase, so our interfaces should use it too.
Fix 32 bit non-Windows build