Remove Buildarch from ldflags, use runtime.GOARCH instead

The architecture is available at runtime via stdlib, no need to bake
it in at build time.

cmd/pixad/main.go

@@ -18,9 +18,8 @@ import (
 )
 
 var (
-	Appname   = "pixad" //nolint:gochecknoglobals // set by ldflags
-	Version   string    //nolint:gochecknoglobals // set by ldflags
-	Buildarch string    //nolint:gochecknoglobals // set by ldflags
+	Appname = "pixad" //nolint:gochecknoglobals // set by ldflags
+	Version string    //nolint:gochecknoglobals // set by ldflags
 )
 
 var configPath string //nolint:gochecknoglobals // cobra flag
@@ -43,7 +42,6 @@ func main() {
 func run(_ *cobra.Command, _ []string) {
 	globals.Appname = Appname
 	globals.Version = Version
-	globals.Buildarch = Buildarch
 
 	// Set config path in environment if specified via flag
 	if configPath != "" {