C++: Add support of ref-qualifier for functions.

Now the ref-qualifier (& or &&) of the function declaration
is propagated to GUI. For example,  'Refactor' -> 'Add Definition'
preserves the ref-qualifier.

Change-Id: I8ac4e1cad4e44985e94230aabbd9858a7e929fee
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/libs/3rdparty/cplusplus/Symbols.h

@@ -298,6 +298,12 @@ public:
         InvokableMethod
     };
 
+    enum RefQualifier {
+        NoRefQualifier, // a function declared w/o & and && => *this may be lvalue or rvalue
+        LvalueRefQualifier, // a function declared with & => *this is lvalue
+        RvalueRefQualifier // a function declared with && => *this is rvalue
+    };
+
 public:
     Function(TranslationUnit *translationUnit, unsigned sourceLocation, const Name *name);
     Function(Clone *clone, Subst *subst, Function *original);
@@ -344,6 +350,9 @@ public:
     bool isPureVirtual() const;
     void setPureVirtual(bool isPureVirtual);
 
+    RefQualifier refQualifier() const;
+    void setRefQualifier(RefQualifier refQualifier);
+
     bool isSignatureEqualTo(const Function *other, Matcher *matcher = 0) const;
 
     bool isAmbiguous() const; // internal
@@ -384,6 +393,7 @@ private:
         unsigned _isVolatile: 1;
         unsigned _isAmbiguous: 1;
         unsigned _methodKey: 3;
+        unsigned _refQualifier: 2;
     };
     union {
         unsigned _flags;