Add aconfig library for external sources

External sources need a aconfig lib to include. Using a dedicated one is easier so that the external source doesn't have to modify other build configs.

Test: build with topic'd cl
Bug: 373461116
Flag: android.os.profiling.system_triggered_profiling_new
Change-Id: I603e77115400b1e9b4b56d49f5d4612df1f8ff9a
3 files changed