add support for smartcards in charon by using the ENGINE API provided by OpenSSL, based on patches by Michael Roßberg.

src/libstrongswan/credentials/builder.c

@@ -35,6 +35,8 @@ ENUM(builder_part_names, BUILD_FROM_FILE, BUILD_END,
 	"BUILD_CA_CERT",
 	"BUILD_CERT",
 	"BUILD_X509_FLAG",
+	"BUILD_SMARTCARD_KEYID",
+	"BUILD_SMARTCARD_PIN",
 	"BUILD_END",
 );