Update vold to prepare package sandboxes for primary volume.

Vold is updated to create package specific sandboxes for primary
volume and mount them at
"/mnt/user/<user-id>/package/<package-name>/<primary-label>".
This will later be mounted at /storage when a new process starts.

Bug: 111890351
Test: Manually verified that a package has access to "/sdcard" and
      "/storage/emulated/0", both of which are just the package specific
      sandboxes and the package doesn't have access to other sandboxes
      and can't see other package names.

Change-Id: I72dc8ae9eb2260a298159c5de18387dad2f9de48
diff --git a/model/VolumeBase.cpp b/model/VolumeBase.cpp
index 429f134..cf3d54e 100644
--- a/model/VolumeBase.cpp
+++ b/model/VolumeBase.cpp
@@ -136,6 +136,16 @@
     return OK;
 }
 
+status_t VolumeBase::setLabel(const std::string& label) {
+    if (mState != State::kChecking) {
+        LOG(WARNING) << getId() << " label change requires state checking";
+        return -EBUSY;
+    }
+
+    mLabel = label;
+    return OK;
+}
+
 android::sp<android::os::IVoldListener> VolumeBase::getListener() {
     if (mSilent) {
         return nullptr;