Fix Help option in headless mode on Windows

Help option failed when Olive was run in its own directory as strrchr
failed. If all else fails basename is equal to argv[0] and we don't
increment in the print statement. Tested on Windows 7.

app/common/commandlineparser.cpp

@@ -115,17 +115,21 @@ void CommandLineParser::PrintHelp(const char* filename)
   }
 
   const char* basename;
+  bool path = true;
 #ifdef Q_OS_WINDOWS
   basename = strrchr(filename, '\\');
   if (!basename) {
     basename = strrchr(filename, '/');
   }
+  if (!basename) {
+    basename = filename;
+    path = false;
+  }
 #else
   basename = strrchr(filename, '/');
 #endif
 
-  printf("Usage: %s [options] %s\n\n", basename + 1, positional_args.toUtf8().constData());
-
+  printf("Usage: %s [options] %s\n\n", path ? basename + 1 : basename, positional_args.toUtf8().constData());
   foreach (const KnownOption& o, options_) {
     QString all_args;