add LTP_DATAROOT and tst_dataroot()

LTP_DATAROOT (test.sh) and tst_dataroot (libltp) define directory
which holds test data files.

If LTPROOT is defined, it is $LTPROOT/testcases/data/$TCID
otherwise it's $CWD/datafiles (where CWD is current working
directory, before any call to tst_tmdir())

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Acked-by: Cyril Hrubis <chrubis@suse.cz>
8 files changed