Forward decls.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72114 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/Spiller.h b/lib/CodeGen/Spiller.h
index e838508..730419b 100644
--- a/lib/CodeGen/Spiller.h
+++ b/lib/CodeGen/Spiller.h
@@ -14,6 +14,9 @@
 
 namespace llvm {
   struct LiveInterval;
+  class LiveIntervals;
+  class MachineFunction;
+  class VirtRegMap;
 
   /// Spiller interface.
   ///