Makefile: preserve links to libraries during make copy_export
Makefile: preserve links to libraries during make copy_export

During "make copy_export" and "make install" the shared library is
copied into the LIBDIR. However "cp" is used, thus the links to the
shared library are not preserved. This patch fixes the problem by using
"cp -a" instead.

Signed-off-by: Marc Kleine-Budde <4a0ea1158d3cc63151119c05b1bff00c0bdbf421@pengutronix.de>
Acked-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org>

prime-zeng/optee_client