Use ANGLE multisample extensions for UWP

drivers/gles2/rasterizer_storage_gles2.cpp

@@ -85,7 +85,9 @@ GLuint RasterizerStorageGLES2::system_fbo = 0;
 #define glClearDepth glClearDepthf
 
 // enable extensions manually for android and ios
+#ifndef UWP_ENABLED
 #include <dlfcn.h> // needed to load extensions
+#endif
 
 #ifdef IPHONE_ENABLED
 
@@ -93,13 +95,18 @@ GLuint RasterizerStorageGLES2::system_fbo = 0;
 //void *glRenderbufferStorageMultisampleAPPLE;
 //void *glResolveMultisampleFramebufferAPPLE;
 #define glRenderbufferStorageMultisample glRenderbufferStorageMultisampleAPPLE
-#elif ANDROID_ENABLED
+#elif defined(ANDROID_ENABLED)
 
 #include <GLES2/gl2ext.h>
 PFNGLRENDERBUFFERSTORAGEMULTISAMPLEEXTPROC glRenderbufferStorageMultisampleEXT;
 PFNGLFRAMEBUFFERTEXTURE2DMULTISAMPLEEXTPROC glFramebufferTexture2DMultisampleEXT;
 #define glRenderbufferStorageMultisample glRenderbufferStorageMultisampleEXT
 #define glFramebufferTexture2DMultisample glFramebufferTexture2DMultisampleEXT
+
+#elif defined(UWP_ENABLED)
+#include <GLES2/gl2ext.h>
+#define glRenderbufferStorageMultisample glRenderbufferStorageMultisampleANGLE
+#define glFramebufferTexture2DMultisample glFramebufferTexture2DMultisampleANGLE
 #endif
 
 #define GL_MAX_SAMPLES 0x8D57