progs/trivial:  Label program windows with actual program name

Each of these programs previously called itself "First Tri" which was a
little confusing.  Could have left one as "First Tri", but the trouble
then is that people would still clone that file & we'd end up with
another thousand first tri apps...
diff --git a/progs/trivial/tri.c b/progs/trivial/tri.c
index d3c6b59..033d6ce 100644
--- a/progs/trivial/tri.c
+++ b/progs/trivial/tri.c
@@ -119,7 +119,7 @@
     type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
     glutInitDisplayMode(type);
 
-    win = glutCreateWindow("First Tri");
+    win = glutCreateWindow(*argv);
     if (!win) {
 	exit(1);
     }