Fix build when hwloc_thread_t isn't defined
Fix build when hwloc_thread_t isn't defined

Found by debugging a problem with Redhat8 sched.h

This commit was SVN r4051.

ggouaillardet/hwloc,ggouaillardet/hwloc,shekkbuilder/hwloc,shekkbuilder/hwloc,ggouaillardet/hwloc,shekkbuilder/hwloc,ggouaillardet/hwloc,shekkbuilder/hwloc