test: use testlib (fourth 100)

X ,s;^// \$G (\$D/)?\$F\.go *$;// compile;g
X ,s;^// \$G (\$D/)?\$F\.go && \$L \$F\.\$A *$;// build;g
X ,s;^// \$G (\$D/)?\$F\.go && \$L \$F\.\$A && \./\$A\.out *$;// run;g
X ,s;^// errchk \$G( -e)? (\$D/)?\$F\.go *$;// errorcheck;g

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5673079

test/ken/divconst.go

@@ -1,4 +1,4 @@
-// $G $D/$F.go && $L $F.$A && ./$A.out
+// run
 
 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style