1s/#undef *\([ABCDEFGHIJKLMNOPQRSTUVWXYZ_]\)/#undef LIBVNCSERVER_\1/
2s/#define *\([ABCDEFGHIJKLMNOPQRSTUVWXYZ_][abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_]*\)\(.*\)/#ifndef LIBVNCSERVER_\1 \
3#define LIBVNCSERVER_\1 \2 \
4#endif/
5