cmd/release: don't ship the api tool source or binary in releases

Fixes golang/go#13030

Change-Id: I3067bdc91ed33ec9f97af2c2da4f77853e10ce73
Reviewed-on: https://go-review.googlesource.com/16802
Reviewed-by: Andrew Gerrand <adg@golang.org>
diff --git a/cmd/release/release.go b/cmd/release/release.go
index 5b8fc7d..65abee2 100644
--- a/cmd/release/release.go
+++ b/cmd/release/release.go
@@ -132,6 +132,8 @@
 	return fmt.Sprintf("%v-%v", b.OS, b.Arch)
 }
 
+func (b *Build) toolDir() string { return "go/pkg/tool/" + b.OS + "_" + b.Arch }
+
 func (b *Build) logf(format string, args ...interface{}) {
 	format = fmt.Sprintf("%v: %s", b, format)
 	log.Printf(format, args...)
@@ -208,6 +210,7 @@
 var postBuildCleanFiles = []string{
 	"VERSION.cache",
 	"pkg/bootstrap",
+	"src/cmd/api",
 }
 
 func (b *Build) buildlet() (*buildlet.Client, error) {
@@ -378,6 +381,9 @@
 	if err := client.RemoveAll(addPrefix(goDir, postBuildCleanFiles)...); err != nil {
 		return err
 	}
+	if err := client.RemoveAll(b.toolDir() + "/api"); err != nil {
+		return err
+	}
 
 	b.logf("Pushing and running releaselet.")
 	f, err := os.Open(releaselet)