Updated warning options for GCC; fixed new warnings.

samples/c/contours.c

@@ -19,6 +19,7 @@ CvSeq* contours = 0;
 
 static void on_trackbar(int pos)
 {
+    (void)pos;
     IplImage* cnt_img = cvCreateImage( cvSize(w,w), 8, 3 );
     CvSeq* _contours = contours;
     int _levels = levels - 3;
@@ -52,6 +53,7 @@ static void findCComp( IplImage* img )
 
 int main(int argc, char* argv[])
 {
+    (void)argc; (void)argv;
     int i, j;
     CvMemStorage* storage = cvCreateMemStorage(0);
     IplImage* img = cvCreateImage( cvSize(w,w), 8, 1 );