A -O3 bootstrap on ia64-linux-gnu crashes building sbitmap.c in stage2.
The problem is that get_vectype_for_scalar_type (type_out = <unsigned
long int>) returns type_out = NULL, and then vect_pattern_recog_1
crashes when it attempts to take the mode of the returned type.

I'm not sure whether returning immediately (like we do for type_in) or
using the original scalar type_out is best.  The latter is what I
regstrapped on ia64-linux-gnu.  Ok to install?