ld-config: Add HIDL memory libs to VNDK-SP

This commit adds libhidlmemory.so and android.hidl.memory@1.0.so to the
exported libs of the `vndk` linker namespace (aka. VNDK-SP).  This is
necessary because some vendors' GLES implementation uses
libhidlmemory.so.  Check http://b/35107583#comment15 for the context.

Bug: 35107583
Test: sailfish boots
Change-Id: Idb5ba4ed4a89795e0e6105d55a84e7f6bbffff51