cmd/pprof: fix help message formatting error

Pprof usage message includes "%" symbols. Misuse of Fprintf caused
the message to be interpreted as a format string and corrupted the usage
message.

Change-Id: I4732b491e2368cff9fdbfe070c125228d6f506fd
Reviewed-on: https://go-review.googlesource.com/115595Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/pprof/readlineui.go

@@ -86,7 +86,7 @@ func (r *readlineUI) print(withColor bool, args ...interface{}) {
 	if withColor {
 		text = colorize(text)
 	}
-	fmt.Fprintf(r.term, text)
+	fmt.Fprint(r.term, text)
 }
 
 // colorize prints the msg in red using ANSI color escapes.