s/#undef  *\([ABCDEFGHIJKLMNOPQRSTUVWXYZ_]\)/#undef LIBVNCSERVER_\1/
s/#define  *\([ABCDEFGHIJKLMNOPQRSTUVWXYZ_][abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_]*\)\(.*\)/#ifndef LIBVNCSERVER_\1 \
#define LIBVNCSERVER_\1 \2 \
#endif/