Add targets of symlinks to genrule's sources am: f45e673a55

Original change: https://android-review.googlesource.com/c/platform/external/libcxx/+/2853249

Change-Id: If403ffa78aec4d307787af9b71707a9551475775
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>