Tools: Skip extracting already existing DBC files

Thanks to MacWarrior, closes #11061

src/tools/map_extractor/System.cpp

@@ -107,6 +107,12 @@ static const char* const langs[] = {"enGB", "enUS", "deDE", "esES", "frFR", "koK
 
 void CreateDir( const std::string& Path )
 {
+    if(chdir(Path.c_str()) == 0)
+    {
+            chdir("../");
+            return;
+    }
+
     int ret;
     #ifdef _WIN32
     ret = _mkdir( Path.c_str());
@@ -1046,6 +1052,9 @@ void ExtractDBCFiles(int locale, bool basicLocale)
     {
         string filename = path;
         filename += (iter->c_str() + strlen("DBFilesClient\\"));
+        
+        if(FileExists(filename.c_str()))
+            continue;
 
         if (ExtractFile(iter->c_str(), filename))
             ++count;