net: use same sendFile for freebsd/dragonfly and solaris

FreeBSD/Dragonfly and Solaris have identical implementations of
sendFile. Keep one and adjust the comments accordingly.

Change-Id: I77b0f88a4816dd6e40f5cb33919c44606401ac6b
Reviewed-on: https://go-review.googlesource.com/104915
Run-TryBot: Tobias Klauser <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>

Author: tklauser

src/net/sendfile_solaris.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build dragonfly freebsd
+// +build dragonfly freebsd solaris
 
 package net
 
@@ -20,7 +20,7 @@ import (
 //
 // if handled == false, sendFile performed no work.
 func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
-	// FreeBSD and DragonFly use 0 as the "until EOF" value.
+	// FreeBSD, DragonFly and Solaris use 0 as the "until EOF" value.
 	// If you pass in more bytes than the file contains, it will
 	// loop back to the beginning ad nauseam until it's sent
 	// exactly the number of bytes told to. As such, we need to
@@ -48,7 +48,7 @@ func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
 		remain = fi.Size()
 	}
 
-	// The other quirk with FreeBSD/DragonFly's sendfile
+	// The other quirk with FreeBSD/DragonFly/Solaris's sendfile
 	// implementation is that it doesn't use the current position
 	// of the file -- if you pass it offset 0, it starts from
 	// offset 0. There's no way to tell it "start from current