vndk: add vendor/lib(64)/vndk for vendor namespace

When the vndk is extended by vendor, the libs in vendor/lib(64)/vndk
will override system/lib(64)/vndk libs. Vendor binaries will search
vndk libs in vendor/lib(64)/vndk prior to system/lib(64)/vndk.

Also, remove a workaround for libsdm-color.so

Bug: 65032513
Test: build and boot check for libsdm-color.so will be loaded on boot
Test: currently no libs exist on vendor/lib(64)/vndk. No test for it
Change-Id: I99ed37eb1a9e92c83533e2d92c9c06db11f01e97