package/openpgm: fix build for non-x86 targets

openpgm-5-3-128 has assembly code for x86 that is not guarded by
architecture defines. A patch to fix that has been merged upstream
some time ago, and the next release will have it. This includes
that patch for the time being.

Fixes: http://autobuild.buildroot.net/results/338291e5bf0671cb7ed7a32cc10e546c7a521acc
Fixes: http://autobuild.buildroot.net/results/3ab6d7f9ee841fa18c1c220d722b1c06ca1fff30
Fixes: http://autobuild.buildroot.net/results/68e840b1fec8f14775cef0b6a14d9b847337324b



Signed-off-by: Alexander Lukichev <alexander.lukichev@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>