recovery: Hide unmountable volumes from selection

* In volume manager, check if new volumes are mountable.

* Check volumes for mountable for inclusion into update list.

* Erase unmountable volumes from volumes vector for consistency with
  the item array.

Change-Id: I89ff6cc05a93afffe5e46b24d70fc368bccaf020
diff --git a/recovery.cpp b/recovery.cpp
index 7b8e32b..864e8cb 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -224,8 +224,13 @@
     items.clear();
     items.push_back("Apply from ADB");
     VolumeManager::Instance()->getVolumeInfo(volumes);
-    for (auto& vitr : volumes) {
-      items.push_back("Choose from " + vitr.mLabel);
+    for (auto vol = volumes.begin(); vol != volumes.end(); /* empty */) {
+      if (!vol->mMountable) {
+        vol = volumes.erase(vol);
+        continue;
+      }
+      items.push_back("Choose from " + vol->mLabel);
+      ++vol;
     }
 
     int chosen = ui->ShowMenu(