[ActivityManager]: Fix the activity visibility state not sync between ActivityManager and WindowManager

Symptom:
When press Home key to home screen, user is able to see the activity's window shown on top of wallpaper and below launcher(widgets).

Root Cause:
The ensureActivitiesVisibleLocked() is called pretty often (for example when a new process bound).
If the top activity "B" was finishing, then the previous activity "A" should be visible.
Therefore, the activity "A" window will be set to visible and then launched activity "A", but it does not updates the visible state in ActivityRecord for "A".
There has a timing issue that if a new activity "C" is started, "C" becomes the new top activity and be resumed.
In that case, Activity "A" window will remain visible even if it is behind a full screen activity "C" because the ActivityRecord.visble of "A" is still false, so the window visibility won't be update.
So when user press home key and back to launcher, the surface of activity "A" will be composed on top of wallpaper.

Solution:
Updates ActivityRecord.visible to true for "A". After "C" is started, the "A" will be called WindowManagerService.setAppVisibility() to set invisible, then called onStop() when execute ensureActivitiesVisibleLocked() again.

Change-Id: I536ba04b95d8d274fea6d679a6493e620bc981e2
GpsLocationProvider: look for config file in /etc/gps.<ro.hardware.gps>.conf

The property ro.hardware.gps can be specifid to allow a single system
image to work with differrent GPS chips.  The HAL layer will use it to load
/system/lib/hw/gps.<ro.hardware.gps>.so.  Add support to GpsLocationProvider
to use the same property to find /etc/gps.<ro.hardware.gps>.conf, falling
back to /etc/gps.conf if the property is not set or the file is not present.

Change-Id: Ib285c4d28b0d0be5e038a1e61822edd8bc6d97d9