[Sema] Allocate SmallVector to the right size.

SmallVector::set_size does not reallocate the vector. Sadly I have no
idea how to test this. The vector never has more than one member in all
of the regression tests.

Found by inspection.

llvm-svn: 243987
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index aff2d1c..0fa7f42 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1657,7 +1657,7 @@
   SmallVector<TemplateParameterList *, 4> TempParamLists;
   unsigned NumTempParamLists = 0;
   if (isFriend && (NumTempParamLists = D->getNumTemplateParameterLists())) {
-    TempParamLists.set_size(NumTempParamLists);
+    TempParamLists.resize(NumTempParamLists);
     for (unsigned I = 0; I != NumTempParamLists; ++I) {
       TemplateParameterList *TempParams = D->getTemplateParameterList(I);
       TemplateParameterList *InstParams = SubstTemplateParams(TempParams);