Add space between // and comment

Enforced by the new clang-format version.

atlas.c

@@ -90,7 +90,7 @@ int character_atlas_render_string(SDL_Renderer* renderer, struct character_atlas
             maxy = items[i]->bitmap.h;
         }
     }
-    //how much do we have to change the letter's size by?
+    // how much do we have to change the letter's size by?
     double str_width_factor = (double)w / (double)str_normal_width;
     SDL_Rect r;
     r.x = x;