opensc: add optional +openssl3 variant

security/opensc/Portfile

@@ -32,9 +32,11 @@ long_description        OpenSC provides a set of libraries and utilities to \
 
 distname                opensc-${version}
 
-# Claims to have 'initial support for OpenSSL 3' but fails to build
-# so keep pinned to version 1.1 for now.
-openssl.branch          1.1
+# Upstream tested against 1.1, so use it as default.
+# (Overriding in variants not working as of 2021-11-13, hence the guard.)
+if {![variant_isset openssl3]} {
+    openssl.branch      1.1
+}
 
 depends_build           port:docbook-xsl-nons \
                         port:gengetopt \
@@ -60,6 +62,11 @@ variant eac description {Enable Extended Access Control (EAC) v2 support} {
     depends_lib-append      port:openpace
     configure.args-replace  --disable-openpace --enable-openpace
 }
+variant openssl3 description {Build against OpenSSL 3 (experimental)} {
+    openssl.branch          3
+    # There will be warnings due to use of deprecated methods so they must not be fatal:
+    configure.args-append   --disable-strict
+}
 variant p11kit description {Use p11-kit as default PKCS#11 module} {
     depends_run             port:p11-kit
 }