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).

builder/library.go

@@ -35,19 +35,6 @@ type Library struct {
 	crt1Source string
 }
 
-// Load the library archive, possibly generating and caching it if needed.
-// The resulting directory may be stored in the provided tmpdir, which is
-// expected to be removed after the Load call.
-func (l *Library) Load(config *compileopts.Config, tmpdir string) (dir string, err error) {
-	job, unlock, err := l.load(config, tmpdir)
-	if err != nil {
-		return "", err
-	}
-	defer unlock()
-	err = runJobs(job, config.Options.Semaphore)
-	return filepath.Dir(job.result), err
-}
-
 // load returns a compile job to build this library file for the given target
 // and CPU. It may return a dummy compileJob if the library build is already
 // cached. The path is stored as job.result but is only valid after the job has