WARNS=3 and C++ on 8.x

Hello!

The graphics/libfpx port can not currently be built on 8.x, because the
WARNS=3, which is set in files/Makefile.bsd triggers -Wsystem-headers.

That setting triggers the following warning:

In file included from /usr/include/c++/4.2/ios:50,
                 from /usr/include/c++/4.2/ostream:45,
                 from /usr/include/c++/4.2/iostream:45,
                 from /work/a/ports/graphics/libfpx/work/libfpx-1.2.0.12/ole/olestorg.cpp:20:
/usr/include/c++/4.2/bits/basic_ios.h: In member function 'void std::basic_ios<_CharT, _Traits>::_M_setstate(std::_Ios_Iostate)':
/usr/include/c++/4.2/bits/basic_ios.h:156: warning: empty body in an if-statement

The port builds fine on 7.x and 6.x. Could the 8.x, please, be fixed?
I mean, the setting, pretty much, assures, that ALL C++ software can't
be built (with WARNS=3, that is), because almost everything uses iostream.

Thanks!

 -mi