Avoid loplugin:staticmethods in non-debug build

Change-Id: I9f98e86556ed4435d24f49b32b848eb9f9a66008

include/xmloff/xmlexp.hxx

@@ -340,7 +340,7 @@ public:
 
     // Check if common attribute list is empty.
 #ifndef DBG_UTIL
-    void CheckAttrList() {}
+    void CheckAttrList() { (void) this; /* avoid loplugin:staticmethods */ }
 #else
     void CheckAttrList();
 #endif

xmloff/source/text/txtimppr.cxx

@@ -241,6 +241,8 @@ void XMLTextImportPropertyMapper::FontDefaultsCheck(
                                                        aAny );
         }
     }
+
+    (void) this; // avoid loplugin:staticmethods
 }
 
 namespace {