- save ir_node* instead of irn_idx in the map (saves irn_idx_map
  lookups)
- in liveness_transfer check register class on the inputs (which is
  cheaper) and only then check the operand

We have simpler code without it, and a heuristic based on
get_irg_last_idx() seems to work as well.

We get a clean SIGSEGV anyway, if they're not fulfilled

So all files in libFirm do this consistently

Profiling uses a magic function named mcount.
When profiling libFirm, these two symbols with the same name lead to strange problems.

rbitset: Handle the edge case that the start position equals the end position in rbitset_next_max().

This fixes rbitset_foreach().

It only measures initializing a single struct.

It is always the same as the irn of the corresponding insn.

Simply return no insn, if it has no constraints.

bechordal: Simplify get_next_free_reg() by priming the set of available registers only with the allocatable registers.