net/http: be consistent about spelling of HTTP/1.x

There was only one use of "HTTP/1.n" compared to "HTTP/1.x":

h2_bundle.go://   "Just as in HTTP/1.x, header field names are strings of ASCII
httputil/dump.go:// DumpRequest returns the given request in its HTTP/1.x wire
httputil/dump.go:// intact. HTTP/2 requests are dumped in HTTP/1.x form, not in their
response.go:// Write writes r to w in the HTTP/1.x server response format,
server.go:      // Request.Body. For HTTP/1.x requests, handlers should read any
server.go:// The default HTTP/1.x and HTTP/2 ResponseWriter implementations
server.go:// The default ResponseWriter for HTTP/1.x connections supports
server.go:// http1ServerSupportsRequest reports whether Go's HTTP/1.x server
server.go:      // about HTTP/1.x Handlers concurrently reading and writing, like
server.go:      // HTTP/1.x from here on.
transport.go:   return fmt.Errorf("net/http: HTTP/1.x transport connection broken: %v", err)

Be consistent.

Change-Id: I93c4c873e500f51af2b4762055e22f5487a625ac
Reviewed-on: https://go-review.googlesource.com/24610Reviewed-by: Andrew Gerrand <adg@golang.org>

src/net/http/response.go

@@ -213,7 +213,7 @@ func (r *Response) ProtoAtLeast(major, minor int) bool {
 		r.ProtoMajor == major && r.ProtoMinor >= minor
 }
 
-// Write writes r to w in the HTTP/1.n server response format,
+// Write writes r to w in the HTTP/1.x server response format,
 // including the status line, headers, body, and optional trailer.
 //
 // This method consults the following fields of the response r: