toolchain-shar-extract.sh: exit when post-relocate-setup.sh fails

toolchain-shar-extract.sh: exit when post-relocate-setup.sh fails

When LD_LIBRARY_PATH is set, post-relocate-setup.sh will fail and
exit properly. But such failure is ignored and the SDK installation
will continue and tell user that things succeed. This is misleading.
So exit immediately if post-relocate-setup.sh fails.

Fixes [Yocto #15586]

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>