testprogram: add option to use SDL_BLENDMODE_MUL

test/testdraw.c

@@ -251,6 +251,9 @@ int main(int argc, char *argv[])
                     } else if (SDL_strcasecmp(argv[i + 1], "mod") == 0) {
                         blendMode = SDL_BLENDMODE_MOD;
                         consumed = 2;
+                    } else if (SDL_strcasecmp(argv[i + 1], "mul") == 0) {
+                        blendMode = SDL_BLENDMODE_MUL;
+                        consumed = 2;
                     }
                 }
             } else if (SDL_strcasecmp(argv[i], "--cyclecolor") == 0) {
@@ -266,7 +269,7 @@ int main(int argc, char *argv[])
         }
         if (consumed < 0) {
             static const char *options[] = {
-                "[--blend none|blend|add|mod]",
+                "[--blend none|blend|add|mod|mul]",
                 "[--cyclecolor]",
                 "[--cyclealpha]",
                 "[num_objects]",