cmd, syscall: use syscall.Mmap on solaris for Go ≥ 1.20

CL 413374 added syscall.Mmap on solaris. Use it in cmd/compile and
cmd/link if the bootstrap toolchain is Go ≥ 1.20.

For #52875
For #54265

Change-Id: I9a0534bf97926eecf0c6f1f9218e855344ba158f
Reviewed-on: https://go-review.googlesource.com/c/go/+/430496
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>

src/cmd/compile/internal/base/mapfile_mmap.go

@@ -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 || dragonfly || freebsd || linux || netbsd || openbsd
-// +build darwin dragonfly freebsd linux netbsd openbsd
+//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || (solaris && go1.20)
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris,go1.20
 
 package base
 

src/cmd/compile/internal/base/mapfile_read.go

@@ -2,8 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd
-// +build !darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd
+//go:build !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !(solaris && go1.20)
+// +build !darwin
+// +build !dragonfly
+// +build !freebsd
+// +build !linux
+// +build !netbsd
+// +build !openbsd
+// +build !solaris !go1.20
 
 package base
 

src/cmd/internal/bio/buf_mmap.go

@@ -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 || dragonfly || freebsd || linux || netbsd || openbsd
-// +build darwin dragonfly freebsd linux netbsd openbsd
+//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || (solaris && go1.20)
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris,go1.20
 
 package bio
 

src/cmd/internal/bio/buf_nommap.go

@@ -2,8 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd
-// +build !darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd
+//go:build !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !(solaris && go1.20)
+// +build !darwin
+// +build !dragonfly
+// +build !freebsd
+// +build !linux
+// +build !netbsd
+// +build !openbsd
+// +build !solaris !go1.20
 
 package bio
 

src/cmd/link/internal/ld/outbuf_mmap.go

@@ -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 aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd
-// +build aix darwin dragonfly freebsd linux netbsd openbsd
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || (solaris && go1.20)
+// +build aix darwin dragonfly freebsd linux netbsd openbsd solaris,go1.20
 
 package ld
 

src/cmd/link/internal/ld/outbuf_nommap.go

@@ -2,8 +2,16 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !windows
-// +build !aix,!darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd,!windows
+//go:build !aix && !darwin && !dragonfly && !freebsd && !linux && !netbsd && !openbsd && !(solaris && go1.20) && !windows
+// +build !aix
+// +build !darwin
+// +build !dragonfly
+// +build !freebsd
+// +build !linux
+// +build !netbsd
+// +build !openbsd
+// +build !solaris !go1.20
+// +build !windows
 
 package ld