core: switch more printf(stderr) to unique messages that can be silenced with HWLOC_HIDE_ERRORS=1
core: switch more printf(stderr) to unique messages that can be silenced with HWLOC_HIDE_ERRORS=1

Useful when debugging failures to merge because of different OS indexes or levels.

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