util/libcrypto.num: fix symbol collision between 1.1.0 and master

util/libcrypto.num: fix symbol collision between 1.1.0 and master

In commit 6decf9436f7, fourteen public symbols were removed from
util/libcrypto.num on the master branch and the following symbols
renumbered. Unfortunately, the symbols `OCSP_resp_get0_signer` and
`X509_get0_authority_key_id` were not adjusted accordingly on the
OpenSSL_1_1_0-stable branch. This commit fixes the collision by
doing a 'double swap'.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6278)