Avoid dominance issues during mode_b lowering.

This fixes opt/fehler269.c.
Fixed typo.
Cleanup using C99.
Improved debug output in some cases.
Handle kept memory Phis appropriately.

This fixes opt/fehler277.c.
Do not optimize a Phi of Stores with different types.

This fixes opt/fehler270.c.
ia32: Directly put the bitfields in ia32_attr_t instead of having another struct needlessly wrapping them.
ia32: Do not set need_64bit_stackent needlessly twice.

It was just done before a few lines above.
ia32: Remove redundant calls to clear_ia32_use_frame()/set_ia32_use_frame() just after/before set_ia32_frame_ent().
ia32: GetEIP does not modify flags.
be: Rename reg_class of struct arch_register_t to cls.

All other structs holding a register class call it cls, too.
be: Remove the thin wrapper macro arch_register_class_mode().
be: Remove the unused thin wrapper macros arch_register_class_index() and arch_register_class_name().
be: Remove the thin wrapper macro arch_register_class_flags().
be: Remove the thin wrapper macro arch_register_class_n_regs().
be: Use be_foreach_out().
be: Use arch_is_irn_not_scheduled().
be: Remove the stale macro arch_env_get_call_abi().
be: Remove the write-only attribute bp from struct arch_env_t.
be: Remove frame input from MemPerm.