Fix race condition in PackageManager.

When Google Play installs 2 apps concurrently (e.g.
personal and work profile) PackageManager can hit a
race condition when connection to media container has
not yet been established but the MCS_BOUND event is
triggered from MCS_UNBIND.

Detailed step by step scenario:
   1. package1 comes in
   2. INIT_COPY (initiate bind, add pending install)
   3. onServiceConnected triggers (MSC_BOUND)
   4. MSC_BOUND, process pending package and schedule MSC_UNBIND
   5. MSC_UNBIND is triggered once the package is verified
   6. service is diconnected
   7. package2 comes in
   8. INIT_COPY (initiate bind, add pending install)
   9. MSC_UNBIND scheduled at step 4
   10. MSC_UNBIND sees that there is a pending package,
       schedules MSC_BIND
   11. MSC_BIND arrives before service is connected and we fail.

Solution: do not fail if we wait for connection.

Bug: 21849046
Change-Id: I39928e1efc81ba64e45c622cc08cb786801d6569