cmd/yacc: use %q to print strings in Toknames

Fixes #12086

Belongs in 1.5

There remains a question of why the Statenames table's elements
are not printed. What purpose does that serve?

Change-Id: I83fd57b81d5e5065c3397a66ed457fc0d1c041bd
Reviewed-on: https://go-review.googlesource.com/13462Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/yacc/yacc.go

@@ -699,18 +699,20 @@ outer:
 		}
 	}
 
-	// put out names of token names
+	// put out names of tokens
 	ftable.WriteRune('\n')
 	fmt.Fprintf(ftable, "var %sToknames = [...]string{\n", prefix)
 	for i := 1; i <= ntokens; i++ {
-		fmt.Fprintf(ftable, "\t\"%v\",\n", tokset[i].name)
+		fmt.Fprintf(ftable, "\t%q,\n", tokset[i].name)
 	}
 	fmt.Fprintf(ftable, "}\n")
 
-	// put out names of state names
+	// put out names of states.
+	// commented out to avoid a huge table just for debugging.
+	// re-enable to have the names in the binary.
 	fmt.Fprintf(ftable, "var %sStatenames = [...]string{", prefix)
 	//	for i:=TOKSTART; i<=ntokens; i++ {
-	//		fmt.Fprintf(ftable, "\t\"%v\",\n", tokset[i].name);
+	//		fmt.Fprintf(ftable, "\t%q,\n", tokset[i].name);
 	//	}
 	fmt.Fprintf(ftable, "}\n")