Revert "cxx11.h: removed the 'evil workaround'"

This reverts commit 2cb9032d76.

lib/cxx11emu.h

@@ -43,7 +43,12 @@ public:
     }
 private:
     void operator&() const;    // whose address can't be taken
-} nullptr = {};  // and whose name is nullptr
+} cppcheck_nullptr_impl = {};  // and whose name is nullptr
+
+// An evil workaround for the inability to disable -Wc++0x-compat using a #pragma.
+// Once -std=c++0x is embraced, the above class can be renamed to nullptr and
+// the define can be removed.
+#define nullptr cppcheck_nullptr_impl
 
 // Static assertions