Constant bits analysis: Skip Tuple nodes.
make parameter const
verify that IJmp successors have Block entities assigned
cfopt: cleanups
remove highlevel op flag

The semantics on when to set this flag were unclear, so there weren't
any real users anyway.
critical_edges: cleanup
irgraph: cleanup, use C99
NoMem must be in the start block
slightly simplify rm_bads code
combo: move Div/Mod compute to separate function, no Bad on div by 0
redo endless loop/keep handling

For details see endless loops section on the homepage.