liblttng_ust.la should depend on liblttng-ust-tracepoint.la, otherwise
there maybe a parallel build issue when building liblttng_ust.la:
ld: cannot find -llttng-ust-tracepoint
[YOCTO #3934]
(From OE-Core rev: b947dbc72b3cd03901112c1bab6ac0b81f1b374f)
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>