* src/common.h (transform_symlinks_option): New global.

* src/create.c (dump_file0): Transform symlink targets only if
explicitly required.  Thanks Cyril Strejc for reporting the
problem.
* src/tar.c (parse_opt): New options --transform-symlinks and
--no-transform-symlinks. New alias --xform to the --transform
option.
* doc/tar.texi: Document --transform-symlinks
* NEWS: Update.
* THANKS: Update.

* src/names.c (name_gather): Use xzalloc.
* src/buffer.c (short_read): Move record size detection before
the loop.