Fix jdk cross-compilation

jdk.nix

@@ -0,0 +1,18 @@
+{ buildPlatform, hostPlatform, jdk11, which, zip, buildPackages }:
+
+if buildPlatform == hostPlatform
+then jdk11
+else (jdk11.override {
+    # libIDL does not compile in cross-compile scenarios.
+    enableGnome2 = false;
+}).overrideAttrs (old: {
+    # lol, nixpkgs can’t get pkgs right
+    # AUTOCONF = "${autoconf}/bin/autoconf";
+    nativeBuildInputs = old.nativeBuildInputs ++ [ which zip ];
+    depsBuildBuild = with buildPackages; [ stdenv.cc autoconf ];
+    configureFlags = old.configureFlags ++ [
+        "--with-jtreg=no"
+        "--disable-hotspot-gtest"
+        "--with-build-jdk=${buildPackages.jdk11}"
+    ];
+})