qdoc: Fixed recursion of \sincelist command handling

QDoc uses a recursive method of resolving all the classes, QML types,
properties, functions etc. added since a specified Qt version.

The code entered the next level of recursion only if its parent had
set a \since version, which was not always the case.

Task-number: QTBUG-41862
Change-Id: I3803ed9ffa472165754358f3906955430a893de1
Reviewed-by: Martin Smith <martin.smith@digia.com>

src/tools/qdoc/qdocdatabase.cpp

@@ -1253,11 +1253,11 @@ void QDocDatabase::findAllSince(InnerNode* node)
                     nsmap.value().insert(name,(*child));
                 }
             }
-            // Recursively find child nodes with since commands.
-            if ((*child)->isInnerNode()) {
-                findAllSince(static_cast<InnerNode *>(*child));
-            }
         }
+        // Recursively find child nodes with since commands.
+        if ((*child)->isInnerNode())
+            findAllSince(static_cast<InnerNode *>(*child));
+
         ++child;
     }
 }