The callee/caller saved information is not constant accross different
ABI's, so don't make it constant. Instead, all BE that still use beabi
provide a callback now.
This allows to implement support for x64_64/Win32 and is a necessary step
for the combined x86 BE.

merge start-block successor with start-block in backend (necessary after equivalent_node_Block is gone)

Fixes opt/localopts2

Because of Phis blocks cannot be equivalent. The cfopt must do all
block merging.

For example, consider the case where block A has one predecessor
block B, which contains a Jmp. Naively, we might exchange(A,B).
However, A might contain a Phi with one operand, then the graph
is broken afterwards, since we move the Phi into B as well.

Difference of idx for Calls with no order relation is stable,
but may lead to circular dependencies. Fixed by looking at
the heights first.

Fixes backend/transform_loop.c (with -O0)

[r28436]

[r28340]

[r28337]

[r28272]

[r28254]

[r28202]

[r28196]

Only makes it hard to search for arch_register_type_* flags.

[r28185]

[r28127]

[r28072]

[r28071]

[r28062]

[r28043]

[r28039]

[r28037]

[r28030]

[r28016]

eliminate the unnecessary and especially confusing concept of a 'code_generator' an isa-interface is enough

[r28009]

[r27992]

[r27970]

[r27924]