objcons call objcons! (#467)

Author: tmigot

src/nlp/api.jl

@@ -118,9 +118,8 @@ Evaluate ``f(x)`` and ``c(x)`` at `x`.
 """
 function objcons(nlp::AbstractNLPModel{T, S}, x::AbstractVector) where {T, S}
   @lencheck nlp.meta.nvar x
-  f = obj(nlp, x)
-  c = cons(nlp, x)
-  return f, c
+  c = S(undef, nlp.meta.ncon)
+  return objcons!(nlp, x, c)
 end
 
 """