ci: don't include prebuilt libraries in the release

These libraries will be automatically built when needed and cached.

The main reason these were needed is for play.tinygo.org, but I've now
prebuilt them there directly (so they don't need to be built for every
tarball).

main.go

@@ -1437,7 +1437,7 @@ func main() {
 		flag.BoolVar(&flagTest, "test", false, "supply -test flag to go list")
 	}
 	var outpath string
-	if command == "help" || command == "build" || command == "build-library" || command == "test" {
+	if command == "help" || command == "build" || command == "test" {
 		flag.StringVar(&outpath, "o", "", "output filename")
 	}
 
@@ -1570,50 +1570,6 @@ func main() {
 
 		err := Build(pkgName, outpath, options)
 		handleCompilerError(err)
-	case "build-library":
-		// Note: this command is only meant to be used while making a release!
-		if outpath == "" {
-			fmt.Fprintln(os.Stderr, "No output filename supplied (-o).")
-			usage(command)
-			os.Exit(1)
-		}
-		if *target == "" {
-			fmt.Fprintln(os.Stderr, "No target (-target).")
-		}
-		if flag.NArg() != 1 {
-			fmt.Fprintf(os.Stderr, "Build-library only accepts exactly one library name as argument, %d given\n", flag.NArg())
-			usage(command)
-			os.Exit(1)
-		}
-		var lib *builder.Library
-		switch name := flag.Arg(0); name {
-		case "compiler-rt":
-			lib = &builder.CompilerRT
-		case "picolibc":
-			lib = &builder.Picolibc
-		default:
-			fmt.Fprintf(os.Stderr, "Unknown library: %s\n", name)
-			os.Exit(1)
-		}
-		tmpdir, err := os.MkdirTemp("", "tinygo*")
-		if err != nil {
-			handleCompilerError(err)
-		}
-		defer os.RemoveAll(tmpdir)
-		spec, err := compileopts.LoadTarget(options)
-		if err != nil {
-			handleCompilerError(err)
-		}
-		config := &compileopts.Config{
-			Options: options,
-			Target:  spec,
-		}
-		path, err := lib.Load(config, tmpdir)
-		handleCompilerError(err)
-		err = copyFile(path, outpath)
-		if err != nil {
-			handleCompilerError(err)
-		}
 	case "flash", "gdb", "lldb":
 		pkgName := filepath.ToSlash(flag.Arg(0))
 		if command == "flash" {