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>
ldd01: remove all -m32/-m64 logic

and build all binaries with same CFLAGS as rest of LTP build.
Also treat lddfile*.so and lddfile.out as data files.

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