syscall: remove Sendfile on NetBSD

NetBSD does not support the sendfile syscall.

Change-Id: I9d8f6145e63011dff1fcd357e1dadd54fe294e85
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/263521
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Benny Siegert <bsiegert@gmail.com>
diff --git a/libgo/go/syscall/libcall_bsd_regfile.go b/libgo/go/syscall/libcall_bsd_regfile.go
index 388c8a7..0b9d01f 100644
--- a/libgo/go/syscall/libcall_bsd_regfile.go
+++ b/libgo/go/syscall/libcall_bsd_regfile.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 darwin dragonfly freebsd netbsd openbsd solaris,amd64 solaris,sparc64
+// +build darwin dragonfly freebsd openbsd solaris,amd64 solaris,sparc64
 
 package syscall
 
diff --git a/libgo/go/syscall/libcall_bsd.go b/libgo/go/syscall/libcall_bsd_sendfile.go
similarity index 87%
rename from libgo/go/syscall/libcall_bsd.go
rename to libgo/go/syscall/libcall_bsd_sendfile.go
index 93f5710..295a1f4 100644
--- a/libgo/go/syscall/libcall_bsd.go
+++ b/libgo/go/syscall/libcall_bsd_sendfile.go
@@ -2,9 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd netbsd openbsd solaris
+// +build darwin dragonfly freebsd openbsd solaris
 
-// BSD library calls.
+// BSD sendfile support.
 
 package syscall