Drawable Renderer (#1570), missing includes

src/mbgl/gfx/context.hpp

@@ -9,6 +9,9 @@
 #include <mbgl/gfx/texture.hpp>
 #include <mbgl/gfx/types.hpp>
 
+#include <memory>
+#include <string>
+
 namespace mbgl {
 
 class PaintParameters;

src/mbgl/gl/context.hpp

@@ -16,10 +16,8 @@
 #include <mbgl/util/noncopyable.hpp>
 
 #include <functional>
-#include <memory>
 #include <vector>
 #include <array>
-#include <string>
 
 namespace mbgl {
 namespace gl {