Corrected issue with shader loading

When using FormatText() several times in same function, returned string is static and so, the same is returned, resulting in failures on shader loading.

examples/models/resources/shaders/glsl330/skybox.vs

@@ -28,5 +28,5 @@ void main()
     vec4 clipPos = projection*rotView*vec4(vertexPosition, 1.0);
 
     // Calculate final vertex position
-    gl_Position = clipPos.xyww;
+    gl_Position = clipPos.xyzw;
 }