Get the canonical path to our temporary directory

When we access ~/.gerritcodereview/tmp we might find out that tmp has
actually be symlinked to a different part of the local filesystem,
such as /tmp.  Resolve the link as early as possible during startup so
that if ~/ is on NFS we remove our dependency on the NFS server as
early as possible and won't be impacted later on should it go down.

Change-Id: Ib631add17338c08c55dd84762dc4fd105308d7c2
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-main/src/main/java/com/google/gerrit/main/GerritLauncher.java

@@ -457,8 +457,12 @@ public final class GerritLauncher {
       }
     }
 
+    try {
+      return tmp.getCanonicalFile();
+    } catch (IOException e) {
       return tmp;
     }
+  }
 
   private GerritLauncher() {
   }