curl: reenable ca-fallback when not using wolfsslSupport

9046258 accidentally swapped the
behaviour, and enabled ca-fallback when using wolfssl and disabled it
without. This effectively disables curl's ability to use the built in CA
stack.

pkgs/tools/networking/curl/default.nix

@@ -96,7 +96,7 @@ stdenv.mkDerivation rec {
       "--without-ca-bundle"
       "--without-ca-path"
       # The build fails when using wolfssl with --with-ca-fallback
-      (lib.withFeature wolfsslSupport "ca-fallback")
+      (lib.withFeature (!wolfsslSupport) "ca-fallback")
       "--disable-manual"
       (lib.withFeatureAs sslSupport "ssl" openssl.dev)
       (lib.withFeatureAs gnutlsSupport "gnutls" gnutls.dev)