Merge branch 'meta'

Merge branch 'meta'

* meta:
  Add utimes/lutimes implementations of _helpers utime() and lutime().
  Replace _helpers.utimensat() with utime() and lutime().
  Test for available nanosecond stat timestamp members.
  Add config.h dependency to _helpers in csetup.py.
  Add -*-shell-script-*- to configure.inc.
  Use FS_IOC_GETFLAGS/FS_IOC_SETFLAGS directly as the preprocessor guards.
  Verify the expected length of saved_errors in tmetadata.py.
  Don't use xstat.lutime() in test-meta.sh when xstat.utime() will do.
  Add meta support for restoring filesystem sockets.
  Add _recognized_file_types(); defer error for unrecognized restore.
  index.py: new format (V3), with inodes, link counts, and 64-bit times.
  Cap timestamps in index to avoid needing to worry about fractional parts.
  index.py: factor out an Entry._fixup_time method.
  Rely on options.parse() for more of the meta and xstat argument processing.
  Remove vestigal clean target comment regarding pybuptest.tmp permissions.
  Add initial timespec behavior tests.
  Return None from bup_set_linux_file_attr() and bup_utimensat().
  Replace os.*stat() with xstat.*stat(); use integer ns for all fs times.
  Drop xstat floating point timestamp support -- use integer ns.
  xstst-cmd.py: test for _have_utimensat rather than _have_ns_fs_timestamps.