[release-branch.go1.15-bundle] icmp, webdav/internal/xml: avoid string(int)

Updates golang/go#32479.
For golang/go#41387.

Change-Id: Ife0c3a2f10afb676af5f2110a9681216122c8808
Reviewed-on: https://go-review.googlesource.com/c/net/+/233900
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit a91f071)
Reviewed-on: https://go-review.googlesource.com/c/net/+/264217
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Alexander Rakoczy <alex@golang.org>

Author: bradfitz

icmp/interface.go

@@ -300,7 +300,7 @@ func parseInterfaceIdent(b []byte) (Extension, error) {
 	}
 	switch ifi.Type {
 	case typeInterfaceByName:
-		ifi.Name = strings.Trim(string(b[4:]), string(0))
+		ifi.Name = strings.Trim(string(b[4:]), "\x00")
 	case typeInterfaceByIndex:
 		if len(b[4:]) < 4 {
 			return nil, errInvalidExtension

webdav/internal/xml/xml.go

@@ -945,7 +945,7 @@ func (d *Decoder) ungetc(b byte) {
 	d.offset--
 }
 
-var entity = map[string]int{
+var entity = map[string]rune{
 	"lt":   '<',
 	"gt":   '>',
 	"amp":  '&',
@@ -1040,7 +1040,7 @@ Input:
 					d.buf.WriteByte(';')
 					n, err := strconv.ParseUint(s, base, 64)
 					if err == nil && n <= unicode.MaxRune {
-						text = string(n)
+						text = string(rune(n))
 						haveText = true
 					}
 				}