Rename gpu_mem.o to gpuMem.o am: 440cf722a9 am: 15748e0a12 am: 82aa83d22e am: d607ad65ef

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/2146977

Change-Id: I1359d7fdaa8fb31a365d94c5235310be4c6d0816
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>