Use SmallVectorImpl& instead of SmallVector to avoid repeating small vector size.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186098 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp
index 861e99b..6be6bf3 100644
--- a/lib/CodeGen/LiveInterval.cpp
+++ b/lib/CodeGen/LiveInterval.cpp
@@ -415,7 +415,7 @@
 void LiveInterval::join(LiveInterval &Other,
                         const int *LHSValNoAssignments,
                         const int *RHSValNoAssignments,
-                        SmallVector<VNInfo*, 16> &NewVNInfo,
+                        SmallVectorImpl<VNInfo *> &NewVNInfo,
                         MachineRegisterInfo *MRI) {
   verify();