This fixes opt/fehler262.c.

This should fix the case where it would remove an unused PhiM in an endless
loop (which is not correct).

A self-loop before the first real value was not recognized before and
could lead to an invalid kept-PhiM removal.

This fixes opt/fehler261.c.

For details see endless loops section on the homepage.

The semantics on when to set this flag were unclear, so there weren't
any real users anyway.

- Mux((a & 1) != 0, 0, b) => -a & b
- Mux((a & 1) == 0, 0, b) => (a - 1) & b

This should fix x86code/funcana_nowrite2.c

This should fix strange overly long immediate values emitted in the
assembler sometimes.

We can now differentiate between objects with compound type and
primitive type.