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/libhwcomposer/hwc_qclient.h b/libhwcomposer/hwc_qclient.h
index 848d8d2..fa1d6b0 100644
--- a/libhwcomposer/hwc_qclient.h
+++ b/libhwcomposer/hwc_qclient.h
@@ -62,6 +62,7 @@
     android::status_t screenRefresh();
     void setExtOrientation(uint32_t orientation);
     void setBufferMirrorMode(uint32_t enable);
+    android::status_t vpuCommand(uint32_t command, uint32_t setting);
 
     hwc_context_t *mHwcContext;
     const android::sp<android::IMediaDeathNotifier> mMPDeathNotifier;