build: Check for Unix98 positional parameter support in printf()
build: Check for Unix98 positional parameter support in printf()

This is equivalent to the AC_FUNC_PRINTF_UNIX98 macro which we use in
configure.ac. There may still be some obscure Unix platforms which don’t
natively support positional parameters, 20 years on.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://gitlab.gnome.org/GNOME/glib/issues/1313

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib