Do not insert instructions, which need to be simulated afterwards.
The only case, which did this, (80bit float/64bit int store with full stack) handles the inserted node locally now.

This place is more natural, because fpop usually happens after an operation.

ia32: Simplify initial check, whether there are values to remove from the fp stack in x87_kill_deads().

x87_create_fpop() already keeps the added fstp.

To remove dead values from the fp stack, it is not necessary to generate any fxch instructions.
fstp can remove any value from the stack.

This way there is one central place to check that the out_count is sane.

The operation that function did was trivial, not abstracting it avoids repeated
get_irn_edge_info() calls in some cases.

new_ir_node() correctly handles oparity_dynamic.

This fixes opt/fehler283.c.