Let LLNDK implementation libraries depend on LLNDK headers

The ABI checker dumps the ABI from the source code of LLNDK
implementation libraries. It needs to filter the ABI by the LLNDK
headers.

This commit adds dependencies from LLNDK implementation libraries to
their export_llndk_headers. The LLNDK header directories are added to
PathDeps. A followup change will pass the directories to the ABI
checker.

Bug: 314010764
Test: make
Change-Id: Ibc2d5eac3d70d9e038e0fd255cd1ebc1044fabbe