Fix hwloc build on 32bit platform with OPTIMIZE=1.

Previously, building hwloc with `OPTIMIZE=1` resulted in this failure:

```
... snip ... 
  CC topology-x86.lo 
/home/vagrant/src/hwloc/include/private/cpuid-x86.h: Assembler messages: 
/home/vagrant/src/hwloc/include/private/cpuid-x86.h:40: Error: symbol 
`Lhwloc1' is already defined 
Makefile:878: recipe for target 'topology-x86.lo' failed 
make[1]: *** [topology-x86.lo] Error 1 
make[1]: Leaving directory '/home/vagrant/src/hwloc/hwloc' 
Makefile:615: recipe for target 'all-recursive' failed 
make: *** [all-recursive] Error 1 
```

Brice Goglin fixed the issue with the changes applied in this pull request.

I applied the patch to the hwloc 1.9.1 in this repo. I also ran the full suite of tests
on linux32 to verify it did not introduce new issues. It did not.

More details here:

  http://www.open-mpi.org/community/lists/hwloc-users/2014/11/1118.php