Remove unused support for SysV shared memory

Remove unused support for SysV shared memory

Chromium no longer uses this.  It used to be that the renderer and NaCl
processes would share SysV shared memory segments with the X11 server on
Linux (because the MIT-SHM extension to X11 relies on SysV shared
memory).  However, with Chromium switching to new compositing methods,
the sandboxed processes no longer share memory with the X server.

Chromium's reference to NaCl's ImportSysvShm() was removed in January
2013: https://src.chromium.org/viewvc/chrome?revision=177732&view=revision

 * Remove NaClDesc type for SysV shared memory segments.

 * SConstruct: Remove reference to non-existent run_srpc_sysv_shm_test.

 * Remove platform qualification test that tests SysV SHM.  This will
   allow Chromium's seccomp-bpf sandbox for NaCl processes to be
   tightened up to disallow use of SysV SHM.

 * Remove AddressMap (dead code) from sel_universal.

BUG=none
TEST=NaCl trybots + Chromium Linux trybot
R=sehr@chromium.org

Committed: https://src.chromium.org/viewvc/native_client?view=rev&revision=13208

[sehr, 2014-05-19 20:29:03]

lgtm

[Mark Seaborn, 2014-05-19 21:03:24]

Committed patchset #1 manually as r13208 (presubmit successful).

[bradn, 2014-05-19 21:42:57]

lgtm