accounts/keystore: add go:build lines (ethereum#23468)

Author: gzliudan

accounts/keystore/watch.go

@@ -14,6 +14,7 @@
 // You should have received a copy of the GNU Lesser General Public License
 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
 
+//go:build (darwin && !ios && cgo) || freebsd || (linux && !arm64) || netbsd || solaris
 // +build darwin,!ios,cgo freebsd linux,!arm64 netbsd solaris
 
 package keystore

accounts/keystore/watch_fallback.go

@@ -14,6 +14,7 @@
 // You should have received a copy of the GNU Lesser General Public License
 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
 
+//go:build (darwin && !cgo) || ios || (linux && arm64) || windows || (!darwin && !freebsd && !linux && !netbsd && !solaris)
 // +build darwin,!cgo ios linux,arm64 windows !darwin,!freebsd,!linux,!netbsd,!solaris
 
 // This is the fallback implementation of directory watching.