powerpc: Add emulator test for the lswi instruction

This test checks some special cases of the lswi instruction. Test
works fine on real hardware, but in QEMU, this reveals a bug with
the final "don't overwrite Ra" test (RA gets destroyed since the
check in QEMU is still wrong).
The code is based on the lswx test by Laurent Vivier.

Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
1 file changed