[TableGen] Use vectors instead of sets for testing intersection. NFC.

[jayfoad]

In a few places we test whether sets (i.e. sorted ranges) intersect by
computing the set_intersection and then testing whether it is empty. For
this purpose it should be more efficient to use a std:vector instead of
a std::set to hold the result of the set_intersection, since insertion
is simpler.

[Pierre-vh]

If I understand correctly this doesn't change the logic of how the intersection is done, just the data structure used to hold the result of the intersection ? If so then LGTM

[s-barannikov]

LGTM as well

[jayfoad]

If I understand correctly this doesn't change the logic of how the intersection is done, just the data structure used to hold the result of the intersection ? If so then LGTM

Exactly. I could not find a simple more efficient way to do the intersection test itself.