Remove DirectFBGL header from Mesa bacause since 1.0.0 DirectFB installs its own header.

Updated to the current DirectFBGL interface (i.e. added GetProcAddress()).
diff --git a/progs/directfb/df_reflect.c b/progs/directfb/df_reflect.c
index ce4d12f..a0e789c 100644
--- a/progs/directfb/df_reflect.c
+++ b/progs/directfb/df_reflect.c
@@ -27,9 +27,9 @@
 #include <math.h>
 
 #include <directfb.h>
+#include <directfbgl.h>
 
 #include <GL/glu.h>
-#include <GL/directfbgl.h>
 
 #include "util/showbuffer.c"
 #include "util/readtex.c"