Default errobj crash

merge UFUNC_ERR_DEFAULT2 variable into UFUNC_ERR_DEFAULT
    
It seems it was added as a precaution to avoid breaking the rather
complicated ufunc code. It effectively disabled the skipping of the
dictionary lookup for the default values for the common case and leading
to hardly tested code in third party libraries like pandas which set the
error state to numpys old default (ignore all).
The skipping improves scalar performance by 2.5-5%.