progs/trivial: add fflushes for cygwin
diff --git a/progs/trivial/tri-unfilled-tri-lit.c b/progs/trivial/tri-unfilled-tri-lit.c
index 775c353..1d42b40 100644
--- a/progs/trivial/tri-unfilled-tri-lit.c
+++ b/progs/trivial/tri-unfilled-tri-lit.c
@@ -39,6 +39,7 @@
    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);
 
   glEnable(GL_LIGHTING);
   glEnable(GL_LIGHT0);