hwc: Add vpu client

Stub implementation of VPU in HWC.
This commit passes through binder calls from HWC
to the VPU library. It also has stub prepare/draw calls
in the VPU client object which can be used to configure
VPU in the composition cycle.

Change-Id: I2606f2884e870448d29ef26e02faac92e157e2c6
diff --git a/libqservice/QService.h b/libqservice/QService.h
index a241d44..de18b59 100644
--- a/libqservice/QService.h
+++ b/libqservice/QService.h
@@ -51,6 +51,7 @@
     virtual android::status_t screenRefresh();
     virtual void setExtOrientation(uint32_t orientation);
     virtual void setBufferMirrorMode(uint32_t enable);
+    virtual android::status_t vpuCommand(uint32_t command, uint32_t setting);
     static void init();
 private:
     QService();