Handle missing libc2d_z160.so error when building customer's Android.

We are working on customer's Android source code. It tooks 6 hours to get the code, and it fails on building procedure, it report libc2d_z160.so error, check error message below:
"
make: *** No rule to make target `out/target/product/imx50_evk/obj/lib/libc2d_z160.so', needed by `out/target/product/imx50_evk/obj/SHARED_LIBRARIES/copybit.imx5x_intermediates/LINKED/copybit.imx5x.so'.  Stop.
"
Find out the reason why this happens.
1. Find libc2d_z160.so, it locate at "~/myandroid/devices/fsl/proprietary/gpu/", in this directory, in fsl-gpu.mk, it already include libc2d_z60.so. So we need check where include the fsl-gpu.mk.
2. We are using imx50_evk for customer configuration, so we enter directory "~/myandroid/devices/fsl/imx50_evk", check AndroidBoard.mk, found there is a line was commented
"#include devices/fsl/proprietary/gpu/fsl-gpu.mk".
3. uncomment this line and build it, it passed, OK.