The barbecue roll and the roll program are not related.
The former is for passive thermal control when the spacecraft is exposed to the Sun and the latter is a maneuver early in the launch sequence to orient the launch vehicle to the proper heading.
For a number of reasons, the space shuttle launch vehicle needs to be oriented "heads down" (the shuttle is positioned "underneath" the external tank) during most of the ascent. It's explained pretty well here:
As we explained in two earlier questions about max q, or maximum
dynamic pressure, the Shuttle reaches a point about one minute after
launch when the pressure force of the atmosphere rushing past the
rapidly accelerating rocket reaches a peak. The roll maneuver is
performed shortly before max q is reached because this "heads-down"
orientation helps alleviate the stresses that the dynamic pressure
loads cause on the vehicle's structure.
The second factor we need to consider is that for each mission, the
Shuttle must launch at a certain azimuth angle in order to be inserted
into the correct orbital plane. Since the launch pad (and therefore
the Shuttle) sits in a fixed position, the Shuttle must perform a roll
maneuver during ascent in order to orient itself to achieve the
desired launch azimuth angle. If it were possible to rotate the launch
pad prior to launch, the pad could simply be rotated to accomodate the
launch azimuth angle, and the Shuttle could launch into a heads-down
orientation while gradually pitching over during ascent.
Finally, the Shuttle orbits such that its cargo bay faces towards the
Earth. The heads-down position assists in communications with the
ground and allows instruments within the cargo bay to be pointed back
towards Earth, which is required for many of the experiments carried
within the bay. There is probably also some psychological benefit to
the crew since they are given spectacular views of home rather than
staring into the cold darkness of the great void of space.
- answer by Aaron Brown, 8 June 2003