openvpn: openssl: explicitly depend on deprecated APIs

OpenVPN as of 2.4.7 uses some OpenSSL APIs that are deprecated in
OpenSSL >= 1.1.0.

Signed-off-by: Magnus Kroken <mkroken@gmail.com>
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com> [white space fix]

package/network/services/openvpn/Makefile

@@ -45,7 +45,7 @@ else
 endif
 endef
 
-Package/openvpn-openssl=$(call Package/openvpn/Default,openssl,OpenSSL,+PACKAGE_openvpn-openssl:libopenssl)
+Package/openvpn-openssl=$(call Package/openvpn/Default,openssl,OpenSSL,+PACKAGE_openvpn-openssl:libopenssl +@OPENSSL_WITH_DEPRECATED)
 Package/openvpn-mbedtls=$(call Package/openvpn/Default,mbedtls,mbedTLS,+PACKAGE_openvpn-mbedtls:libmbedtls)
 Package/openvpn-nossl=$(call Package/openvpn/Default,nossl,plaintext (no SSL))