Build a vector rvalue from an array of elements.
“vec_type” should be a vector type, created using gcc_jit_type_get_vector().
“num_elements” should match that of the vector type.
This entrypoint was added in LIBGCCJIT_ABI_10; you can test for its presence using
#ifdef LIBGCCJIT_HAVE_gcc_jit_context_new_rvalue_from_vector