make sure color picker and color swatch buttons have rnaindex of -1.

Some were 0 some -1, but this messed up reporting - making it think that only red was being changed for each button.

source/blender/editors/interface/interface_widgets.c

@@ -2588,6 +2588,8 @@ static void widget_swatch(uiBut *but, uiWidgetColors *wcol, rcti *rect, int stat
 	col[3] = 1.0f;
 
 	if (but->rnaprop) {
+		BLI_assert(but->rnaindex == -1);
+
 		if (RNA_property_subtype(but->rnaprop) == PROP_COLOR_GAMMA)
 			color_profile = FALSE;