[Bug target/81628] New: Backport r250637 and r250638 to the powerpcspe* target

["asolokha at gmx dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81628

            Bug ID: 81628
           Summary: Backport r250637 and r250638 to the powerpcspe* target
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
                CC: andrewjenner at gcc dot gnu.org, charlet at gcc dot gnu.org
  Target Milestone: ---
            Target: powerpcspe-*-linux-gnu*

Revisions r250637 and r250638 remove -mno-lra (i.e. reload-based RA) from the
rs6000 target, leaving -mlra as a stub. They also remove -mlra from one
testcase specific to SPE targets.

However, SPE support was factored out to its own target during the stage 1 of
the gcc 8 branch lefiteme, after the point when LRA had been switched on for
rs6000 by default, so -mlra and -mno-lra still make difference there. AFAICT,
tests in testsuite/gcc.target/powerpc are shared by both targets now, so the
changes in testsuite by the aforementioned revisions also affect both of them.
Furtunately, changes in testsuite made there are safe, as they don't change RA
used by the SPE target when compiling them.

Nevertheless, it seems reasonable to disable reload for SPE as well, until two
targets did not diverge too much.