Add annotation to all assembly files to turn off stack-execute bit

See discussion in http://tracker.ceph.com/issues/10114

Building with these changes allows output from readelf like this:

 $ readelf -lW src/.libs/librados.so.2 | grep GNU_STACK
  GNU_STACK      0x000000 0x0000000000000000 0x0000000000000000 0x000000
0x000000 RW  0x8

(note the absence of 'X' in 'RW')

Fixes: #10114
Signed-off-by: Dan Mick <dan.mick@redhat.com>
(cherry picked from commit 06a245a9845c0c126fb3106b41b2fd2bc4bc4df3)
erasure-code isa-l: remove duplicated lines (fix warning)

06a245a added a section def to assembly files; I added it twice to
this file.  There's no damage, but a compiler warning (on machines with
yasm installed)

Signed-off-by: Dan Mick <dan.mick@redhat.com>
(cherry picked from commit 10f6ef185a9d09e396e94036ec90bfe8a0738ce9)
Merge pull request #2963 from ceph/wip-10114-giant

Wip 10114 giant

Reviewed-by: Loic Dachary <ldachary@redhat.com>