Fix ticket #179 (preprocessor issues)

http://apps.sourceforge.net/trac/cppcheck/ticket/179

src/preprocessor.cpp

@@ -865,10 +865,14 @@ std::string Preprocessor::expandMacros(std::string code)
                     {
                         params.push_back(par);
                         par = "";
+                    }
+                    else if (code[pos2] == ' ')
+                    {
+
                     }
                     else if (parlevel >= 1)
                     {
-                        par += std::string(1, code[pos2]);
+                        par.append(1, code[pos2]);
                     }
                 }
             }

test/testpreprocessor.cpp

@@ -108,7 +108,7 @@ private:
 
         TEST_CASE(stringify);
         TEST_CASE(stringify2);
-        // TODO TEST_CASE(stringify3);
+        TEST_CASE(stringify3);
         TEST_CASE(ifdefwithfile);
         TEST_CASE(pragma);
     }