Add break for default cases

Visual Studio has an option to search all files in a solution, so I
did a search in there for "default:" looking for any missing break
statements.

I've left out default statements that return something, and that throw
something, even if via ThrowInvalidType. UNREACHABLE leads towards throw

R_THROW macro leads towards a return

src/yuzu_cmd/emu_window/emu_window_sdl2_vk.cpp

@@ -84,6 +84,7 @@ EmuWindow_SDL2_VK::EmuWindow_SDL2_VK(InputCommon::InputSubsystem* input_subsyste
     default:
         LOG_CRITICAL(Frontend, "Window manager subsystem not implemented");
         std::exit(EXIT_FAILURE);
+        break;
     }
 
     OnResize();

src/yuzu_cmd/yuzu.cpp

@@ -351,6 +351,7 @@ int main(int argc, char** argv) {
                          "additional help.\n\nError Code: {:04X}-{:04X}\nError Description: {}",
                          loader_id, error_id, static_cast<Loader::ResultStatus>(error_id));
         }
+        break;
     }
 
     system.TelemetrySession().AddField(Common::Telemetry::FieldType::App, "Frontend", "SDL");