Fixed recently introduced FP when C-Style casting nullpointers

lib/checkother.cpp

@@ -499,6 +499,9 @@ void CheckOther::warningOldStylePointerCast()
             if (tok->strAt(1) == "const")
                 tok = tok->next();
 
+            if (tok->strAt(4) == "0") // Casting nullpointers is safe
+                continue;
+
             // Is "type" a class?
             if (_tokenizer->getSymbolDatabase()->isClassOrStruct(tok->strAt(1)))
                 cstyleCastError(tok);

test/testother.cpp

@@ -1468,6 +1468,12 @@ private:
                                  "};");
         ASSERT_EQUALS("[test.cpp:3]: (style) C-style pointer casting\n", errout.str());
 
+        checkOldStylePointerCast("class SomeType;\n"
+                                 "class X : public Base {\n"
+                                 "    X() : Base((SomeType*)0) {}\n"
+                                 "};");
+        ASSERT_EQUALS("", errout.str());
+
         // #5560
         checkOldStylePointerCast("class C;\n"
                                  "\n"