lapi/rt_sigaction.h: mark rt_stub functions as used

Commit cb2313789a21fb ("ltp_rt_sigaction: SPARC fixes for -O0") did
not consider the situation where the compiler (-O2) optimizes out
rt_stub functions and the labels we define in them, since these
functions are not used explicitly anywhere.

To avoid this let's explicitly mark them as used.
__attribute__((used)) should not bring any new build errors, because
it's supported by gcc and clang (at least since 3.0).

Signed-off-by: Stanislav Kholmanskikh <stanislav.kholmanskikh@oracle.com>
1 file changed