frontend: Remove V-Sync option from UI

The V-Sync option is fundamentally broken in Citra, so let's do the same as yuzu and remove it entirely for SDL2 and at least from the frontend for QT.
(It was also only used by 7.3% of users)

src/citra/config.cpp

@@ -121,7 +121,7 @@ void Config::ReadValues() {
     Settings::values.use_shader_jit = sdl2_config->GetBoolean("Renderer", "use_shader_jit", true);
     Settings::values.resolution_factor =
         static_cast<u16>(sdl2_config->GetInteger("Renderer", "resolution_factor", 1));
-    Settings::values.use_vsync = sdl2_config->GetBoolean("Renderer", "use_vsync", false);
+    Settings::values.vsync_enabled = sdl2_config->GetBoolean("Renderer", "vsync_enabled", false);
     Settings::values.use_frame_limit = sdl2_config->GetBoolean("Renderer", "use_frame_limit", true);
     Settings::values.frame_limit =
         static_cast<u16>(sdl2_config->GetInteger("Renderer", "frame_limit", 100));

src/citra/default_ini.h

@@ -119,7 +119,7 @@ resolution_factor =
 
 # Whether to enable V-Sync (caps the framerate at 60FPS) or not.
 # 0 (default): Off, 1: On
-use_vsync =
+vsync_enabled =
 
 # Turns on the frame limiter, which will limit frames output to the target game speed
 # 0: Off, 1: On (default)

src/citra/emu_window/emu_window_sdl2.cpp

@@ -163,7 +163,7 @@ EmuWindow_SDL2::EmuWindow_SDL2(bool fullscreen) {
     OnResize();
     OnMinimalClientAreaChangeRequest(GetActiveConfig().min_client_area_size);
     SDL_PumpEvents();
-    SDL_GL_SetSwapInterval(Settings::values.use_vsync);
+    SDL_GL_SetSwapInterval(Settings::values.vsync_enabled);
     LOG_INFO(Frontend, "Citra Version: {} | {}-{}", Common::g_build_fullname, Common::g_scm_branch,
              Common::g_scm_desc);
     Settings::LogSettings();