I could see cutting down "Empty Chairs at Empty Tables" maybe, but cutting it entirely? Heresy! That was probably Marius' best song!
Well, aside from "Red and Black" but I'd hate to see that go too.
Between "Beggars at the Feast" and "Dog Eat Dog," keep "Dog Eat Dog" - it's so sinister and drives home the "Miserables" part of the show.
Cutting the Friends of the ABC down makes the most sense, but it seems a real shame. Looking over the Wiki entry with the musical numbers, you could probably cut everything from "A Little Fall of Rain" to "The Final Battle" with the exception of "Bring Him Home." Losing "Drink With Me" would really suck, but I guess cuts have to be made. For that matter, compress things so that "A Little Fall of Rain" happens just before the final battle, with "Bring Him Home" happening at the same time as "On My Own."
You could probably cut out all of the prologue except "Work Song" too. Or, since this is a movie, go straight to "At the End of the Day" and establish Valjean's backstory in a limited way via a brief text into. Nothing's gonna be perfect and losing that driving opening will stink, but that seems like a reasonable cut for time as well.