openssl: strip the test suite

openssl: strip the test suite

The test suite is huge because every test binary is statically linked to
libssl and/or libcrypto. This bloats the size of the -dbg package hugely,
so strip the test suite before packaging.

This reduces the size of openssl-dbg by 90% from ~1.2GB to ~120MB, and
reduces the size of the build tree from ~1.9GB to ~800MB.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>