Add ld.config.txt for wearables

When BOARD_VNDK_VERSION is set, the required VNDK libs for vendor
modules are installed in vndk directory.
The default namespace configuration cannot reach those directories
and fails to link the required libs.
By installing ld.config.txt, the namespace configurations for each
build target will be selected automatically. This does not affect
the devices that requires default namespace configurations.

Bug: 74242105
Test: lunch sdk_gwear_x86-userdebug; make -j; emulator
Change-Id: Ib1097846fcd9c123184b13b6fbcfcb9a72ca3d97