openssl: remove dependency on relative_symlinks class

openssl: remove dependency on relative_symlinks class

Although the relative_symlinks class converts any absolute symlinks
in ${D} into relative symlinks automatically, it's a little clearer
to create relative symlinks directly where possible.

Signed-off-by: Andre McCurdy <armccurdy@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>