This helper returns the VT-number for the given VT if, and only if, it
is a real VT. In all other cases 0 is returned.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Major overhaul of the build system. This introduces symbol-versioning for
all exported libraries. Please note that none of these libraries is
stable, yet!
Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>