Update git submodules

* Update plugins/download-commands from branch 'master'
  - Merge branch 'stable-2.15'
    
    * stable-2.15:
      CloneWithCommitMsgHook: Stop passing --insecure to curl
    
    Change-Id: I16b388db6a5d36b8a60d9c9ab09d9a793bad24a2
    
  - Merge branch 'stable-2.14' into stable-2.15
    
    * stable-2.14:
      CloneWithCommitMsgHook: Stop passing --insecure to curl
    
    Change-Id: I4ff216985885be55959a79f430ee1894fb5ba1d7
    
  - CloneWithCommitMsgHook: Stop passing --insecure to curl
    
    Validating certs is an important feature of HTTPS that we should not
    disable, especially when downloading code that is going to be trusted.
    
    This "curl" invocation does not take place until after a successful
    "git clone", so the -k option would not be useful for dealing with
    misconfigured https servers.  Any configuration that needs -k would
    already be broken because of the "git clone" that comes before it.
    
    Reported-by: Gert van Dijk <gertvdijk@gmail.com>
    Bug: Issue 7562
    Change-Id: Ibe14bba5c1ce30a771515ff7985796aa1b8cdadf
    
diff --git a/plugins/download-commands b/plugins/download-commands
index 6ee2462..ddbd127 160000
--- a/plugins/download-commands
+++ b/plugins/download-commands
@@ -1 +1 @@
-Subproject commit 6ee246245b9200062e753d1c6943d5782cb7fee0
+Subproject commit ddbd12781fd4b3156625608ee608950ab370b9a3