[Bug target/116854] GCC incorrectly assumes all CPUs where -march=native resolves to -march=bdver4 will have RDRND support

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116854

--- Comment #14 from Jonathan Wakely <redi at gcc dot gnu.org> ---
FWIW, libstdc++ checks for RDRND support at runtime using __get_cpuid_max, even
when it was detected when compiling.