Do not use link field during out-edge verification.
Fixed invalid use of out edges.

Since safely iterating over out edges caches the next edges, we cannot
recursively move Proj nodes along with their operands.
If the Proj node is the cached one this causes the out edges to suddenly iterate
over another block.

This fixes opt/fehler279.c and opt/fehler280.c.
Unreachable code removal cannot cope with Tuple nodes.

This fixes opt/fehler278.c.
Fixed condition for creating a Phi node.

This fixes opt/fehler281.c.