buildroot

ltp-testsuite: bump version and use autotargets

Reworking ltp-testsuite is needed in order to get rid of some
thread-specific options that will be cleaned-up in the next commit.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>