[Bug target/104930] built-in function requires "-flax-vector-conversions" to get better warning

[linkw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104930

--- Comment #2 from Kewen Lin <linkw at gcc dot gnu.org> ---
It's regressed from r12-5752-gd08236359eb229, in the new bif infrastructure we
don't use the type opaque_V4SI_type_node for prototype of overloaded built-in
functions any more.