Update go branch to Go 1.21.

Starting with Go 1.21, build tags select the language version. We currently
have several `go:build go1.1` tags, which were intended to act as "true" tags.
But that will break with 1.21. So replace them with "!false".

Fixes #9568.

PiperOrigin-RevId: 576020779

.github/workflows/go.yml

@@ -45,7 +45,7 @@ jobs:
         fetch-depth: 0
     - uses: actions/setup-go@v3.5.0
       with:
-        go-version: '1.20'
+        go-version-file: 'go.mod'
     - run: tools/go_branch.sh
     - run: git checkout go && git clean -xf . && go build ./...
     - if: github.event_name == 'push'

go.mod

@@ -1,6 +1,6 @@
 module gvisor.dev/gvisor
 
-go 1.20
+go 1.21.1
 
 require (
 	github.com/BurntSushi/toml v1.2.1

pkg/coverage/coverage.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 // Package coverage provides an interface through which Go coverage data can
 // be collected, converted to kcov format, and exposed to userspace.

pkg/crypto/crypto_stdlib.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package crypto
 

pkg/flipcall/ctrl_futex.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package flipcall
 

pkg/memutil/mmap.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package memutil
 

pkg/sentry/arch/arch_x86_impl.go

@@ -12,9 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build (amd64 || 386) && go1.1
+//go:build (amd64 || 386) && !false
 // +build amd64 386
-// +build go1.1
+// +build !false
 
 package arch
 

pkg/sentry/hostfd/hostfd_linux.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package hostfd
 

pkg/sentry/kernel/kernel_opts.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package kernel
 

pkg/sentry/kernel/threads_impl.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package kernel
 

pkg/sentry/socket/hostinet/sockopt_impl.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package hostinet
 

pkg/sentry/state/state_metadata.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package state
 

pkg/shim/runtimeoptions/runtimeoptions_cri.go

@@ -13,8 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package runtimeoptions
 

pkg/shim/runtimeoptions/v14/runtimeoptions_cri.go

@@ -13,8 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package v14
 

pkg/test/testutil/testutil_runfiles.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package testutil
 

runsc/boot/filter/config_profile.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package filter
 

runsc/boot/pprof/pprof.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 // Package pprof provides a stub to initialize custom profilers.
 package pprof

runsc/cmd/mitigate_extras.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package cmd
 

runsc/config/config_bundles.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 package config
 

runsc/flag/flag.go

@@ -12,8 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//go:build go1.1
-// +build go1.1
+//go:build !false
+// +build !false
 
 // Package flag wraps flag primitives.
 package flag