Fixed #585 (Preprocessor: Don't check the same configuration twice)

http://sourceforge.net/apps/trac/cppcheck/ticket/585

src/preprocessor.cpp

@@ -643,10 +643,16 @@ std::list<std::string> Preprocessor::getcfgs(const std::string &filedata)
                     break;
                 if (*it == "1")
                     continue;
+
+                // don't add "T;T":
+                // treat two and more similar nested conditions as one
+                if (def != *it)
+                {
                     if (! def.empty())
                         def += ";";
                     def += *it;
                 }
+            }
 
             if (std::find(ret.begin(), ret.end(), def) == ret.end())
                 ret.push_back(def);