GPU Memory: install gpu_mem.o and integrate libgpumem

This change integrates libgpumem into gpuservice. gpu_mem.o c program is
required in the blueprint so that gpu_mem.o will be compiled and
installed at /system/etc/bpf/.

This change also adds a proper CleanSpec.mk for gpu_mem.o

Bug: 154524735
Test: adb shell dumpsys gpu --gpumem
Change-Id: Iad09d061691ffd4cf0fc4bde63cb6f0ae459aa27
Merged-In: Iad09d061691ffd4cf0fc4bde63cb6f0ae459aa27
diff --git a/services/gpuservice/GpuService.h b/services/gpuservice/GpuService.h
index d1c3aab..6797868 100644
--- a/services/gpuservice/GpuService.h
+++ b/services/gpuservice/GpuService.h
@@ -28,6 +28,7 @@
 
 namespace android {
 
+class GpuMem;
 class GpuStats;
 
 class GpuService : public BnGpuService, public PriorityDumper {
@@ -74,6 +75,7 @@
     /*
      * Attributes
      */
+    std::unique_ptr<GpuMem> mGpuMem;
     std::unique_ptr<GpuStats> mGpuStats;
     std::mutex mLock;
     std::string mDeveloperDriverPath;