target/3920: [PPC] wrong register number for CTR in stabs

[Mattias Engdegård]

Gcc 3.2.1 behaves identically to 3.0.1 in this respect:
I cannot get gcc to emit Stabs/DWARF info saying that a variable lives
in CTR, so even if gcc has the wrong number for it, this has no ill
effect. Even if a variable lives in CTR inside a loop, the Stabs/DWARF
will have it in some general integer register instead.
The latter is a quality-of-debug-info bug.