Added the AMD equivalent for NvOptimusEnablement.

Source/Urho3D/Graphics/Direct3D11/D3D11Graphics.cpp

@@ -69,9 +69,10 @@
 #pragma warning(disable:4355)
 #endif
 
-// On Intel / NVIDIA setups prefer the NVIDIA GPU
+// Prefer the high-performance GPU on switchable GPU systems
 extern "C" {
-    __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
+    __declspec(dllexport) DWORD NvOptimusEnablement = 1;
+    __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
 }
 
 namespace Urho3D

Source/Urho3D/Graphics/Direct3D9/D3D9Graphics.cpp

@@ -66,9 +66,10 @@
 #pragma warning(disable:4355)
 #endif
 
-// On Intel / NVIDIA setups prefer the NVIDIA GPU
+// Prefer the high-performance GPU on switchable GPU systems
 extern "C" {
-    __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
+    __declspec(dllexport) DWORD NvOptimusEnablement = 1;
+    __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
 }
 
 // Fix missing define in MinGW headers

Source/Urho3D/Graphics/OpenGL/OGLGraphics.cpp

@@ -70,10 +70,11 @@
 #endif
 
 #ifdef WIN32
-// On Intel / NVIDIA setups prefer the NVIDIA GPU
+// Prefer the high-performance GPU on switchable GPU systems
 #include <windows.h>
 extern "C" {
-    __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
+    __declspec(dllexport) DWORD NvOptimusEnablement = 1;
+    __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 1;
 }
 #endif