gl: examples: fix c++ code for -Wreturn-aggregate

.. and use #ifdef instead of #if

tests/examples/gl/generic/cubeyuv/main.cpp

@@ -73,10 +73,9 @@ static void identityCallback (GstElement *src, GstBuffer  *buffer, GstElement* t
     nbFrames++ ;
     if (GST_BUFFER_TIMESTAMP(buffer) - last_timestamp >= 1000000000)
     {
-        std::ostringstream oss ;
-        oss << "video framerate = " << nbFrames ;
-        std::string s(oss.str()) ;
-        g_object_set(G_OBJECT(textoverlay), "text", s.c_str(), NULL);
+        gchar *s = g_strdup_printf ("video framerate = %d", nbFrames);
+        g_object_set(G_OBJECT(textoverlay), "text", s, NULL);
+        g_free (s);
         last_timestamp = GST_BUFFER_TIMESTAMP(buffer) ;
         nbFrames = 0 ;
     }

tests/examples/gl/generic/doublecube/main.cpp

@@ -73,10 +73,9 @@ static GstPadProbeReturn textoverlay_sink_pad_probe_cb (GstPad *pad, GstPadProbe
   nbFrames++ ;
   if (GST_BUFFER_TIMESTAMP(info->data) - last_timestamp >= 1000000000)
   {
-    std::ostringstream oss;
-    oss << "video framerate = " << nbFrames ;
-    std::string s(oss.str());
-    g_object_set(G_OBJECT(textoverlay), "text", s.c_str(), NULL);
+    gchar *s = g_strdup_printf ("video framerate = %d", nbFrames);
+    g_object_set(G_OBJECT(textoverlay), "text", s, NULL);
+    g_free (s);
     last_timestamp = GST_BUFFER_TIMESTAMP(info->data) ;
     nbFrames = 0;
   }

tests/examples/gl/generic/recordgraphic/main.cpp

@@ -19,7 +19,7 @@
  */
 
 #include <GL/gl.h>
-#if __WIN32__ || _WIN32
+#if defined(__WIN32__) || defined(_WIN32)
 # include <GL/glext.h>
 #endif
 #include <gst/gst.h>