eqVneq w.r.t. 0

[affeldt-aist]

https://github.com/affeldt-aist/trajectories/blob/1be5acf4fcbeaabe96a52c1ae491f24bfea81f3a/theories/conv.v#L129

shouldn't this be eqVneq ((1 - t) * (1 - u)) 1. instead to limit the use of subr_eq0