* expr.c (do_store_flag): Expand vector comparison by
building an appropriate VEC_COND_EXPR.
* c-typeck.c (build_binary_op): Typecheck vector comparisons.
(c_objc_common_truthvalue_conversion): Adjust.
* tree-vect-generic.c (do_compare): Helper function.
(expand_vector_comparison): Check if hardware supports
vector comparison of the given type or expand vector
piecewise.
(expand_vector_operation): Treat comparison as binary
operation of vector type.
(expand_vector_operations_1): Adjust.