trivial: add line-flat.c
diff --git a/progs/trivial/SConscript b/progs/trivial/SConscript
index 480630e..0333418 100644
--- a/progs/trivial/SConscript
+++ b/progs/trivial/SConscript
@@ -26,6 +26,7 @@
 	'fs-tri',
 	'line-clip',
 	'line-cull',
+	'line-flat',
 	'line-smooth',
 	'line-stipple-wide',
 	'line-userclip-clip',