Clang: Improve function definition completion

Insert argument list together with completion.

Task-number: QTCREATORBUG-20826
Change-Id: I4aa9faaa04bcd3ca014306aad27843c2b4419d3c
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/libs/clangsupport/codecompletion.h

@@ -45,6 +45,7 @@ public:
     enum Kind : quint32 {
         Other = 0,
         FunctionCompletionKind,
+        FunctionDefinitionCompletionKind,
         FunctionOverloadCompletionKind,
         TemplateFunctionCompletionKind,
         ConstructorCompletionKind,