headers: don't provide system endiannes conversion functions

instead of providing endiannes conversion functions by default, we should
provide our own versions to avoid pulling in windows headers into the
public interface

Signed-off-by: Tim Blechmann <tim@klingt.org>
scsynth: SC_Graph - pull in Windows headers in the beginning

Signed-off-by: Tim Blechmann <tim@klingt.org>
sclang: portmidi - remove pthread cruft

Signed-off-by: Tim Blechmann <tim@klingt.org>
plugins: Test ugens - print via Print instead of printf

Signed-off-by: Tim Blechmann <tim@klingt.org>