Rename some functions for consistency.

Every other function in Redeclarable.h was using Decl instead of Declaration.

llvm-svn: 192900
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index 94f05e9..5007eea 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -308,7 +308,7 @@
                                              ClassTemplateDecl *PrevDecl) {
   AdoptTemplateParameterList(Params, cast<DeclContext>(Decl));
   ClassTemplateDecl *New = new (C) ClassTemplateDecl(DC, L, Name, Params, Decl);
-  New->setPreviousDeclaration(PrevDecl);
+  New->setPreviousDecl(PrevDecl);
   return New;
 }
 
@@ -974,7 +974,7 @@
                                          NamedDecl *Decl,
                                          VarTemplateDecl *PrevDecl) {
   VarTemplateDecl *New = new (C) VarTemplateDecl(DC, L, Name, Params, Decl);
-  New->setPreviousDeclaration(PrevDecl);
+  New->setPreviousDecl(PrevDecl);
   return New;
 }