libstdc++: Fix OpenBSD ctype_base masks Building on recent OpenBSD fails because the mask macros have been redefined. Use the new macros if available. libstdc++-v3/ChangeLog: * config/os/bsd/openbsd/ctype_base.h: Use _CTYPE prefixed macros if available. Signed-off-by: Pietro Monteiro <pietro@sociotechnical.xyz>