- gave vid_autoswitch CVAR a priority over vk_device selection

Try to mimic OpenGL GPU selection behavior with MoltenVK when automated graphics switching is disabled
The CVAR isn't exposed in menu and its target audience is advanced users only

src/posix/cocoa/i_video.mm

@@ -367,6 +367,12 @@ public:
 
 			[ms_window setContentView:vulkanView];
 
+			if (!vid_autoswitch)
+			{
+				// CVAR from pre-Vulkan era has a priority over vk_device selection
+				setenv("MVK_CONFIG_FORCE_LOW_POWER_GPU", "1", 0);
+			}
+
 			try
 			{
 				m_vulkanDevice = new VulkanDevice();