Make apex availability of fmtlib_ndk explicit am: 9ceaceb712 am: 6e91310212 am: fa67a88c90

Original change: https://android-review.googlesource.com/c/platform/external/fmtlib/+/2894402

Change-Id: I0e036fb17ce4914091b136e40f7a55690a6b1a2a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>