progs/trivial: add fflushes for cygwin
diff --git a/progs/trivial/tri-cull.c b/progs/trivial/tri-cull.c
index c6bcf44..c71ad9a 100644
--- a/progs/trivial/tri-cull.c
+++ b/progs/trivial/tri-cull.c
@@ -60,6 +60,7 @@
    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);
    cull();
 }