fix bug setting the wrong address offset in initLights()

the first offset should have been the entire size of the 'header', aka)
the LightsBuffer structure

src/tangerine.cpp

@@ -307,7 +307,7 @@ initLights(MemoryArena* arena, GLContext* gl_ctx, u32 max_lights)
 	lb->max_d_lights = max_lights;
 
 	// NOTE: set offsets for array pointers
-	lb->pl_positions = (glm::vec4*) arenaGetAddressOffset(lb, 8 * sizeof(u32));
+	lb->pl_positions = (glm::vec4*) arenaGetAddressOffset(lb, sizeof(*lb));
 	u32 arr_size = max_lights * sizeof(glm::vec4);
 	lb->pl_colors =
 		(glm::vec4*) arenaGetAddressOffset(lb->pl_positions, arr_size);