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.

The only user of this information (bechordal) can just check the register requirement type.

beirgmod: Do not set registers for the Perm results in insert_Perm_before() just to clear them afterwards.

This was missed when changing insert_Perm_after() to insert_Perm_before().

The only user of this information (bechordal) can just check, whether a register is assigned.

arch_register_type_virtual is sufficient.

They must match, even for joker registers.

bearch: Assert, instead of test, that the register requirement is not arch_register_req_type_none in arch_reg_is_allocatable().

If it is, something is very wrong.