Fix a possible warning in the XML output code. Stolen from OMPI trunk.
Fix a possible warning in the XML output code.
Stolen from OMPI trunk.

This commit was SVN r4017.

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