bring in changes from the 24pathfix branch (now that 24 is on head)
Merge remote branch 'upstream/master' into pathfix
update PLFS code to use new plfs_physpathinfo architecture.
Merge branch 'master' into pathfix
fix a signed/unsigned compare warningerror
make mlog_stderr work properly
two fixes:
 - Container::resolvepath_finish: mimic old hashing behavior when
                                  operating on the top level mount

 - plfs_getattr: had a condition reversed causing getattr to malfunction
two changes:
 - update FlatFileSystem::resolvepath_finish() to match container one
   (so that we properly mimic the old resolve path for the top-level dir)

 - Flat_fd::open was using this->back before it was init'd.  fixed.
Merge branch 'master' into pathfix
PLFS better error handling

Changes PLFS return type to have every function return a consistent type.
reroute plfs_expand_path to use plfs_resolvepath.
switch fuse from find_mount_point to plfs_resolvepath.
find_best_mount_point: make sure we are at the end of
the matching cleanlogical segment before reporting a hit.
convert plfs_get_logical_fs and plfs_get_filetype to use
plfs_resolvepath.
remove unused prototype
remove obsolete get_backend(), find_mount_point(), plfs_iterate_backends().
oops, fix FileOp::RenameOp to use physpath (the compiler didn't
catch this one because the API didn't change).

retire find_all_expansions(), no longer used.
i forgot to remove adplfs_num_host_dirs() a while ago (in the
iostore changes), it is no longer used.
missed a couple of PLFS_EXITs
- replace stripPrefixPath() with skipPrefixPath().   does the same
  basic thing, but with less overhead (no need to malloc strings or
  allocate PATH_MAX on the stack).

- retire find_mount_point_using_tokens(), expandPath(), and ExpansionInfo