Please pull from 'for_paulus' branch

[Paul Mackerras]

Andreas Schwab writes:

> The assembler should be called with -a64, which has the effect of
> defaulting to -mppc64.

Yes, the assembler is called with -a64, but that doesn't appear to
have the effect of defaulting to -mppc64.

[Alan: this thread is about the fact that compiling C code with "gcc
-m64 -mcpu=powerpc64" will give assembler errors, complaining about
instructions like sldi, whereas compiling with "gcc -m64" doesn't.]

Paul.