[AST] Follow-up to r297972, add default value for setGetterName/setSetterName if a source-loc is not provided.

Fixes lldb build.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@297974 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/DeclObjC.h b/include/clang/AST/DeclObjC.h
index 642aa80..c2a09cd 100644
--- a/include/clang/AST/DeclObjC.h
+++ b/include/clang/AST/DeclObjC.h
@@ -858,14 +858,14 @@
 
   Selector getGetterName() const { return GetterName; }
   SourceLocation getGetterNameLoc() const { return GetterNameLoc; }
-  void setGetterName(Selector Sel, SourceLocation Loc) {
+  void setGetterName(Selector Sel, SourceLocation Loc = SourceLocation()) {
     GetterName = Sel;
     GetterNameLoc = Loc;
   }
 
   Selector getSetterName() const { return SetterName; }
   SourceLocation getSetterNameLoc() const { return SetterNameLoc; }
-  void setSetterName(Selector Sel, SourceLocation Loc) {
+  void setSetterName(Selector Sel, SourceLocation Loc = SourceLocation()) {
     SetterName = Sel;
     SetterNameLoc = Loc;
   }