fsmagic: sort array by value and use bsearch for faster lookup

fsmagic: sort array by value and use bsearch for faster lookup

* defs.h (xlat_search): New prototype.
* util.c (xlat_bsearch_compare, xlat_search): New functions.
* file.c (sprintfstype): Use xlat_search for fsmagic lookup.
* xlat/fsmagic.in: Sort by value and mark as not NULL-terminated.
* tests/statfs.c: New file.
* tests/statfs.test: New test.
* tests/Makefile.am (check_PROGRAMS): Add statfs.
(statfs_CFLAGS): Define.
(TESTS): Add statfs.test.
* tests/.gitignore: Add statfs.