progs/trivial: add fflushes for cygwin
diff --git a/progs/trivial/tri-unfilled-userclip.c b/progs/trivial/tri-unfilled-userclip.c
index aab5abc..0dec0bf 100644
--- a/progs/trivial/tri-unfilled-userclip.c
+++ b/progs/trivial/tri-unfilled-userclip.c
@@ -41,6 +41,7 @@
    fprintf(stderr, "GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
    fprintf(stderr, "GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
    fprintf(stderr, "GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
+   fflush(stderr);
 
    glClearColor(0.0, 0.0, 1.0, 0.0);	
    glClipPlane(GL_CLIP_PLANE0, plane);