single argument panic

note that sortmain.go has been run through hg gofmt;
only the formatting of the day initializers changed.
i'm happy to revert that formatting if you'd prefer.

stop on error in doc/progs/run

R=r
CC=golang-dev
https://golang.org/cl/850041
diff --git a/test/cmp1.go b/test/cmp1.go
index 12e65be..db0a486 100644
--- a/test/cmp1.go
+++ b/test/cmp1.go
@@ -70,6 +70,7 @@
 	m[ic] = 1
 	m[id] = 2
 	if m[ic] != 2 {
-		panic("m[ic] = ", m[ic])
+		println("m[ic] = ", m[ic])
+		panic("bad m[ic]")
 	}
 }