progs/trivial: Use glew where needed.

Builds on windows now.
diff --git a/progs/trivial/point-param.c b/progs/trivial/point-param.c
index 96544a0..1edeec3 100644
--- a/progs/trivial/point-param.c
+++ b/progs/trivial/point-param.c
@@ -22,7 +22,7 @@
  * OF THIS SOFTWARE.
  */
 
-#define GL_GLEXT_PROTOTYPES
+#include <GL/glew.h>
 #include <math.h>
 #include <stdio.h>
 #include <string.h>
@@ -146,6 +146,8 @@
 	exit(1);
     }
 
+    glewInit();
+
     Init();
 
     glutReshapeFunc(Reshape);