[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 #25 from Andreas Schwab <sch...@linux-m68k.org> ---
The other packages I tested (libgcrypt, openblas, pixman, sleef, volk) now
build sucessfully.