[Bug testsuite/116757] check_effective_target_fileio uses deprecated function resulting in UNSUPPORTED

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116757

--- Comment #3 from Sam James <sjames at gcc dot gnu.org> ---
libstdc++ has its own check_v3_target_fileio with a fixed file, no tmpnam.