va_copy() needs sys/cdefs.h?

[Klaus Heinz]

Hi,

I am working on a package and the configure stage (running on Dragonfly
1.4.0 in a qemu VM) does not detect a working va_copy() although the
test includes stdarg.h. A closer inspection revealed that va_copy()
depends on __ISO_C_VISIBLE being defined and this happens for me only if
I include sys/cdefs.h as well.
On NetBSD, this is not needed.

Is this the correct behaviour and should such a patch be fed back to the
software's authors?

ciao
     Klaus