fix shader for Apple devices

src/rtt.cpp

@@ -259,7 +259,7 @@ void RTT::clear_mask(glm::bool4 mask, glm::vec4 color)
 {
     // save old state
     std::array<GLboolean, 4> old_mask;
-    glGetBooleanv(GL_COLOR_WRITEMASK, std::data(old_mask));
+    glGetBooleanv(GL_COLOR_WRITEMASK, old_mask.data());
 
     // clear with mask
     glColorMask(mask.r, mask.g, mask.b, mask.a);