Fix FTBFS on powerpc with recent binutils

Fix FTBFS on powerpc with recent binutils

Forwarded: no
Last-Update: 2015-11-23

A recent modification in binutils (see
https://sourceware.org/ml/binutils/2015-04/msg00332.html) introduced a change
in the way the ppc assembly instructions "dcbt" and "dcbtst" are handled.
When compiling on a generic ppc processor, the 3-arguments form of those
instructions is no longer accepted, and one must instead use a 2-arguments
form (ignoring the TH argument).

Incidentally, the binutils change also fixed a bug in the way those
instructions were handled. On a generic ppc processor, they used to be
interpreted in the so-called "embedded" form ("dcbt TH, RA, RB", only used on
some embedded machines), while they should have been interpreted in the
so-called "server" form ("dcbt RA, RB, TH"). The ATLAS assembly directive were
apparently written in "server" form, and were therefore mis-assemblied.

Ideally, this patch should be improved in order to use the TH argument on
machines that support it (only needed in atlas_prefetch.h; other instances use
the default zero value for TH).
Last-Update: 2015-11-23
Gbp-Pq: Name powerpc-dcbt.patch