openjdk8: work around gnupatch latest feature of not following symlinks, even when --follow-symlinks is specified.

pkgs/development/compilers/openjdk/fix-java-home-jdk8.patch

@@ -0,0 +1,15 @@
+--- a/hotspot/src/os/linux/vm/os_linux.cpp  2015-02-04 21:14:39.000000000 +0100
++++ b/hotspot/src/os/linux/vm/os_linux.cpp  2015-05-19 16:17:29.960107613 +0200
+@@ -2304,10 +2304,8 @@
+   assert(ret, "cannot locate libjvm");
+   char *rp = NULL;
+   if (ret && dli_fname[0] != '\0') {
+-    rp = realpath(dli_fname, buf);
++    snprintf(buf, buflen, "%s", dli_fname);
+   }
+-  if (rp == NULL)
+-    return;
+
+   if (Arguments::created_by_gamma_launcher()) {
+     // Support for the gamma launcher.  Typical value for buf is
+

pkgs/development/compilers/openjdk/openjdk8.nix

@@ -50,11 +50,16 @@ let
   '';
   prePatch = ''
     # despite --with-override-jdk the build still searchs here
-    ln -s "../jdk-${repover}" "jdk";
+    # GNU Patch bug, follow symlinks only follow the last symlink..
-    ln -s "../hotspot-${repover}" "hotspot";
+    mv "../jdk-${repover}" "jdk";
+    mv "../hotspot-${repover}" "hotspot";
+  '';
+  postPatch = ''
+    mv jdk "../jdk-${repover}";
+    mv hotspot "../hotspot-${repover}";
   '';
   patches = [
-    ./fix-java-home.patch
+    ./fix-java-home-jdk8.patch
     ./read-truststore-from-env-jdk8.patch
     ./currency-date-range-jdk8.patch
   ];