Softfloat library does not support long double anyway.

(Hannes ancient technique based on the Proj-mode is deprecated)

They really are const before lowering. So only mark the function
as non-const after lowering

This reverts commit 72c631f3.

This commit also adds a generic Alloc/Free lowering helper
Unfortunately we often produce invalid code, because currently our
stackpointer wiring logic is too weak and produces invalid results for
example when using alloca in a loop.

This fixes opt/fehler200.c.

Old version used parameter.

Backends can configure CopyB lowering, so that it's possible to keep
CopyB nodes in a certain size range for special backend-specific
optimizations.  Furthermore, large CopyBs are turned into memcpy calls.

The part, which does not handle Phis is now recomputing block info,
because converting Cond -> Jmp, might make this info obsolete.

Additionally, it can now remove empty Jmp blocks with more than one
control flow predecessor, provided the origin block has no Phis.

Now cfopt should now be idempotent
(at least the part not handling Phis).

Code was taken from cmp_call_dependency in beabi.c which handles the
situation correctly.

Old version breaks for files which do not contain any functions because
in this case, emit_routine never gets called.