LibGL: Add defines and stubs for glBlendFunc()

Author: https://github.com/sunverwerth
Commit: 279737642c
Pull-request: https://github.com/SerenityOS/serenity/pull/7156

Userland/Libraries/LibGL/GLBlend.cpp

@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Stephan Unverwerth <s.unverwerth@gmx.de>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "GL/gl.h"
+#include "GLContext.h"
+
+extern GL::GLContext* g_gl_context;
+
+void glBlendFunc(GLenum sfactor, GLenum dfactor)
+{
+    return g_gl_context->gl_blend_func(sfactor, dfactor);
+}