cmd/compile/internal/gc: move functions from util.go to lex.go

Moves the functions:
        isSpace(int) bool
        isAlpha(int) bool
        isDigit(int) bool
        isAlnum(int) bool
        plan9quote(string) string

Passes go build -toolexec 'toolstash -cmp' -a std.

Change-Id: I6f946981abb6f29b047ad90d5c117847e826789f
Reviewed-on: https://go-review.googlesource.com/14952
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/lex.go

@@ -840,6 +840,33 @@ func cannedimports(file string, cp string) {
 	incannedimport = 1
 }
 
+func isSpace(c int) bool {
+	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
+}
+
+func isAlpha(c int) bool {
+	return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z'
+}
+
+func isDigit(c int) bool {
+	return '0' <= c && c <= '9'
+}
+func isAlnum(c int) bool {
+	return isAlpha(c) || isDigit(c)
+}
+
+func plan9quote(s string) string {
+	if s == "" {
+		return "''"
+	}
+	for _, c := range s {
+		if c <= ' ' || c == '\'' {
+			return "'" + strings.Replace(s, "'", "''", -1) + "'"
+		}
+	}
+	return s
+}
+
 func isfrog(c int) bool {
 	// complain about possibly invisible control characters
 	if c < ' ' {

src/cmd/compile/internal/gc/util.go

@@ -5,7 +5,6 @@ import (
 	"runtime"
 	"runtime/pprof"
 	"strconv"
-	"strings"
 )
 
 func (n *Node) Line() string {
@@ -18,34 +17,6 @@ func atoi(s string) int {
 	return int(n)
 }
 
-func isSpace(c int) bool {
-	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
-}
-
-func isAlnum(c int) bool {
-	return isAlpha(c) || isDigit(c)
-}
-
-func isAlpha(c int) bool {
-	return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z'
-}
-
-func isDigit(c int) bool {
-	return '0' <= c && c <= '9'
-}
-
-func plan9quote(s string) string {
-	if s == "" {
-		return "''"
-	}
-	for _, c := range s {
-		if c <= ' ' || c == '\'' {
-			return "'" + strings.Replace(s, "'", "''", -1) + "'"
-		}
-	}
-	return s
-}
-
 // strings.Compare, introduced in Go 1.5.
 func stringsCompare(a, b string) int {
 	if a == b {