tar: change -a from meaning "lzma" to mean "autodetect by extension"

function                                             old     new   delta
tar_main                                            1026    1100     +74
packed_usage                                       33311   33329     +18
tar_longopts                                         309     325     +16
vfork_compressor                                     246     210     -36
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(add/remove: 0/0 grow/shrink: 3/1 up/down: 108/-36)            Total: 72 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed