unix: remove darwin build tags from asm_bsd_{386,arm}.s

CL 316769 dropped support for darwin/386 and darwin/arm. Remove the
respective build tags from asm_bsd_{386,arm}.s as well.

Change-Id: Ic7c64446aaf80298c2ae893e2103c394ace2b01c
Reviewed-on: https://go-review.googlesource.com/c/sys/+/323389
Trust: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/unix/asm_bsd_386.s b/unix/asm_bsd_386.s
index 7f29275..e0fcd9b 100644
--- a/unix/asm_bsd_386.s
+++ b/unix/asm_bsd_386.s
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin || freebsd || netbsd || openbsd) && gc
-// +build darwin freebsd netbsd openbsd
+//go:build (freebsd || netbsd || openbsd) && gc
+// +build freebsd netbsd openbsd
 // +build gc
 
 #include "textflag.h"
diff --git a/unix/asm_bsd_arm.s b/unix/asm_bsd_arm.s
index 98ebfad..d702d4a 100644
--- a/unix/asm_bsd_arm.s
+++ b/unix/asm_bsd_arm.s
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build (darwin || freebsd || netbsd || openbsd) && gc
-// +build darwin freebsd netbsd openbsd
+//go:build (freebsd || netbsd || openbsd) && gc
+// +build freebsd netbsd openbsd
 // +build gc
 
 #include "textflag.h"