progs/trivial: add fflushes for cygwin
diff --git a/progs/trivial/tri.c b/progs/trivial/tri.c
index d99d587..d44cb6a 100644
--- a/progs/trivial/tri.c
+++ b/progs/trivial/tri.c
@@ -40,6 +40,7 @@
    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(0.3, 0.1, 0.3, 0.0);
 }