Fix msvc14 compile errors

cgohlke · cgohlke · commit ffddf89a99e2 · 2015-07-27T13:14:20.000-07:00
diff --git a/src/_backend_agg.h b/src/_backend_agg.h
@@ -8,6 +8,7 @@
 
 #include <cmath>
 #include <vector>
+#include <algorithm>
 
 #include "agg_alpha_mask_u8.h"
 #include "agg_conv_curve.h"
