Use SmallVectorImpl instead of SmallVector as method argument to avoid specifying vector size.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185513 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CriticalAntiDepBreaker.h b/lib/CodeGen/CriticalAntiDepBreaker.h
index df13dd3..565d20b 100644
--- a/lib/CodeGen/CriticalAntiDepBreaker.h
+++ b/lib/CodeGen/CriticalAntiDepBreaker.h
@@ -103,7 +103,7 @@
                                       unsigned AntiDepReg,
                                       unsigned LastNewReg,
                                       const TargetRegisterClass *RC,
-                                      SmallVector<unsigned, 2> &Forbid);
+                                      SmallVectorImpl<unsigned> &Forbid);
   };
 }