Rename DiagnoseIncompleteType to RequireCompleteType, and update the documentation to reflect the fact that we can instantiate templates here

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@66421 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index 1ef579f..10a3a9d 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -283,7 +283,7 @@
 
   virtual TypeResult ActOnTypeName(Scope *S, Declarator &D);
 
-  bool DiagnoseIncompleteType(SourceLocation Loc, QualType T, unsigned diag,
+  bool RequireCompleteType(SourceLocation Loc, QualType T, unsigned diag,
                               SourceRange Range1 = SourceRange(),
                               SourceRange Range2 = SourceRange(),
                               QualType PrintType = QualType());