trim: Prune uninteresting calls while trimming (unless --no-prune is passed)

trim: Prune uninteresting calls while trimming (unless --no-prune is passed)

Examine the CALL_FLAG_UNINTERESTING flag and leave out these calls
when trimming. These calls are generally the calls that have no side
effects, (such as query functions). Some calls without side effects
might be considered interesting, (such as glGetError returning a
non-zero error).

This pruning behavior can be avoided by passing the new --no-prune
option (or the new --exact option which is identical to passing both
--no-prune and -no-deps).