v5.4.1
sysdefs.h: Don't include strings.h anymore.
Bump version and soname for 5.4.1.
Build: Prepare to support Automake's subdir-objects.
xzdiff: Add support for .lz files.
xz: Include <strings.h> in suffix.c if needed for strcasecmp().
Build: Add support for translated man pages using po4a.