hello_xr: Fix OpenGL build on MinGW

Author: rpavlik

src/tests/hello_xr/graphicsplugin_opengl.cpp

@@ -1,4 +1,10 @@
 #include "pch.h"
+
+#ifdef __MINGW32__
+#define GL_ATTRIBUTE __attribute__((stdcall))
+#else
+#define GL_ATTRIBUTE
+#endif
 #include "common.h"
 #include "geometry.h"
 #include "graphicsplugin.h"
@@ -135,16 +141,14 @@ struct OpenGLGraphicsPlugin : public IGraphicsPlugin {
 #endif
 
         glEnable(GL_DEBUG_OUTPUT);
-        glDebugMessageCallback(
-            [](GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message,
-               const void* userParam) {
-                ((OpenGLGraphicsPlugin*)userParam)->DebugMessageCallback(source, type, id, severity, length, message);
-            },
-            this);
+        glDebugMessageCallback(&OpenGLGraphicsPlugin::DebugMessageCallbackTrampoline, this);
 
         InitializeResources();
     }
-
+    static void GL_ATTRIBUTE DebugMessageCallbackTrampoline(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length,
+                                                            const GLchar* message, const void* userParam) {
+        ((OpenGLGraphicsPlugin*)userParam)->DebugMessageCallback(source, type, id, severity, length, message);
+    }
     void InitializeResources() {
         glGenFramebuffers(1, &m_swapchainFramebuffer);