[Bug target/110812] Check availability of builtins at expand time

[schwab--- via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110812

--- Comment #15 from Andreas Schwab <sch...@linux-m68k.org> ---
I would expect that LTO use the same machinery as the target attribute.

#pragma riscv intrinsic "vector"
int vl;
__attribute__((target("arch=+v"))) void v () { vl = __riscv_vsetvl_e8m8 (0); }