Before, the active spline index and the active point index were always
cleared. Now the active index is only cleared when the curve/surface is
deleted. This was accomplished by making the surface patch delete
function handle that correctly. The spline deletion already handled it.
This fixes only vertex deletion mode.
Fixes problem mentioned in T101160.
Differential Revision: https://developer.blender.org/D16133
f3f0ea8dc2