Replace unlzma, gunzip, bunzip2 with pack tool -d invocation. * lib/am/distdir.am (distcheck): Use lzma -d, gzip -d, bzip2 -d, instead of the respective un$tool invocation, to avoid depending on another tool. * THANKS: Update. Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>