meson: warn if the default value from meson.get_cross_property() is being used
Projects such as glib have tests that execute code to check their behaviour, and
in cross-compilation environments where they can't execute code fall back on
meson.get_cross_property() with a default value. These default values may not
be appropriate: for example if glib can't verify that vsprintf() isn't broken it
assumes that it is, and embeds the gnulib copy of vsprintf() instead of using
glibc's implementation.
Add a warning whenever the default value for get_cross_property() is used so
that we can tell this is happening and set the value appropriately.
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
