internal/iapclient: don't fail if the gomote directory exists

Mkdir fails if the directory exists, and we want MkdirAll anyway.

Change-Id: Ie4260b520cf819018fee95778d6fbf874357bfd2
Reviewed-on: https://go-review.googlesource.com/c/build/+/378397
Trust: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/internal/iapclient/iapclient.go b/internal/iapclient/iapclient.go
index 356877e..13b9ce1 100644
--- a/internal/iapclient/iapclient.go
+++ b/internal/iapclient/iapclient.go
@@ -54,7 +54,7 @@
 	if err != nil {
 		return err
 	}
-	err = os.Mkdir(filepath.Join(configDir, "gomote"), 0755)
+	err = os.MkdirAll(filepath.Join(configDir, "gomote"), 0755)
 	if err != nil {
 		return err
 	}