Remove automatic RPATH

Before OpenSSL 1.1.0, binaries were installed in a non-standard
location by default, and runpath directories were therefore added in
those binaries, to make sure the executables would be able to find the
shared libraries they were linked with.

With OpenSSL 1.1.0 and on, binaries are installed in standard
directories by default, and the addition of runpath directories is
therefore not needed any more.

Reviewed-by: Rich Salz <rsalz@openssl.org>