strconv: consistent parameter names for ParseUint

If ParseUint is like ParseInt it should have the same parameter
names, thus rename b to to base as in ParseInt's documentation.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6453152

src/pkg/strconv/atoi.go

@@ -44,7 +44,7 @@ func cutoff64(base int) uint64 {
 }
 
 // ParseUint is like ParseInt but for unsigned numbers.
-func ParseUint(s string, b int, bitSize int) (n uint64, err error) {
+func ParseUint(s string, base int, bitSize int) (n uint64, err error) {
 	var cutoff, maxVal uint64
 
 	if bitSize == 0 {
@@ -57,32 +57,32 @@ func ParseUint(s string, b int, bitSize int) (n uint64, err error) {
 		err = ErrSyntax
 		goto Error
 
-	case 2 <= b && b <= 36:
+	case 2 <= base && base <= 36:
 		// valid base; nothing to do
 
-	case b == 0:
+	case base == 0:
 		// Look for octal, hex prefix.
 		switch {
 		case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
-			b = 16
+			base = 16
 			s = s[2:]
 			if len(s) < 1 {
 				err = ErrSyntax
 				goto Error
 			}
 		case s[0] == '0':
-			b = 8
+			base = 8
 		default:
-			b = 10
+			base = 10
 		}
 
 	default:
-		err = errors.New("invalid base " + Itoa(b))
+		err = errors.New("invalid base " + Itoa(base))
 		goto Error
 	}
 
 	n = 0
-	cutoff = cutoff64(b)
+	cutoff = cutoff64(base)
 	maxVal = 1<<uint(bitSize) - 1
 
 	for i := 0; i < len(s); i++ {
@@ -100,19 +100,19 @@ func ParseUint(s string, b int, bitSize int) (n uint64, err error) {
 			err = ErrSyntax
 			goto Error
 		}
-		if int(v) >= b {
+		if int(v) >= base {
 			n = 0
 			err = ErrSyntax
 			goto Error
 		}
 
 		if n >= cutoff {
-			// n*b overflows
+			// n*base overflows
 			n = 1<<64 - 1
 			err = ErrRange
 			goto Error
 		}
-		n *= uint64(b)
+		n *= uint64(base)
 
 		n1 := n + uint64(v)
 		if n1 < n || n1 > maxVal {