[Bug-tar] --auto-compress command line option

[Denis Excoffier]

About tar-1.19.90:

1) thank you for the new --auto-compress (-a) command line option!

2) there is a missing "--" in doc/tar.info-1, line 7543, it should read:

The compression option is `-z' (`--gzip') to create a `gzip' compressed
archive, `-j' (`--bzip2') to create a `bzip2' compressed archive,
`--lzma' to create an LZMA compressed archive and `-Z' (`--compress') to
use `compress' program.

instead of:

The compression option is `-z' (`--gzip') to create a `gzip' compressed
archive, `-j' (`--bzip2') to create a `bzip2' compressed archive,
`lzma' to create an LZMA compressed archive and `-Z' (`--compress') to
use `compress' program.

3) i suggest that the location of the compress/gzip/bzip2/lzma programs
be settable at configure time, and that the tar executable uses the PATH
only when not set at configure time or not found in the indicated place.
The tar_help() would have to be augmented.