clangbackend: Fix crash

We cannot assume that a Q_PROPERTY name is on the same line as the
keyword.

Fixes: QTCREATORBUG-24746
Change-Id: Ic2e02291e24c1abbaf72881b540a26c82899cb2c
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

tests/unit/unittest/data/highlightingmarks.cpp

@@ -699,3 +699,35 @@ private:
 template <int i, int j> struct S { };
 template <int i> using spec = S<i, 1>;
 spec<2> s;
+
+class Property {
+    Q_PROPERTY(
+
+            const
+
+            volatile
+
+            unsigned
+
+            long
+
+            long
+
+            *
+
+            prop
+
+            READ
+
+            getProp
+
+            WRITE
+
+            setProp
+
+            NOTIFY
+
+            propChanged
+
+            )
+};