tls_ctx_set_tls_versions: move verify_flags to where it is used

tls_ctx_set_tls_versions: move verify_flags to where it is used

Minor cleanup of this function now that we are allowed to write C99: move
(and rename) flags to the code where it's actually used to improve
readability.

(I originally did this as part of the tls-version-{min,max} patch for
openssl 1.1, but that made the diff hard to read.)

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20171126141555.25930-3-steffan@karger.me>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg15931.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>