ARC: MWDT: libc: add _exit support

Default weak _exit implementation from ARC MWDT libs
calls _exit_halt from startup libs. As we are going to
get rid of startup libs usage let's implement _exit
stub.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>
1 file changed