Revert "curl: disable fetchpatch passthru test on darwin"

This was fixed at some point; I can reproduce the issue before the
original commit, but not now.

This reverts commit e6b37d5a61.

pkgs/tools/networking/curl/default.nix

@@ -202,6 +202,7 @@ stdenv.mkDerivation (finalAttrs: {
     inherit opensslSupport openssl;
     tests = {
       withCheck = finalAttrs.finalPackage.overrideAttrs (_: { doCheck = true; });
+      fetchpatch = tests.fetchpatch.simple.override { fetchpatch = (fetchpatch.override { fetchurl = useThisCurl fetchurl; }) // { version = 1; }; };
       curlpp = useThisCurl curlpp;
       coeurl = useThisCurl coeurl;
       haskell-curl = useThisCurl haskellPackages.curl;
@@ -215,8 +216,6 @@ stdenv.mkDerivation (finalAttrs: {
       pkg-config = testers.testMetaPkgConfig finalAttrs.finalPackage;
     } // lib.optionalAttrs (stdenv.hostPlatform.system != "x86_64-darwin") {
       static = pkgsStatic.curl;
-    } // lib.optionalAttrs (!stdenv.hostPlatform.isDarwin) {
-      fetchpatch = tests.fetchpatch.simple.override { fetchpatch = (fetchpatch.override { fetchurl = useThisCurl fetchurl; }) // { version = 1; }; };
     };
   };