implement support for functions which may optionally fail to load am: 2464ddb0df

Original change: https://googleplex-android-review.googlesource.com/c/platform/system/bpf/+/11905498

Change-Id: I218d67bbcd9196973904bde92512d3382738c497
tree: 5009769ace4840970df3fd372922e8956da93d05
  1. bpfloader/
  2. libbpf_android/
  3. progs/
  4. Android.bp
  5. MODULE_LICENSE_APACHE2
  6. NOTICE
  7. OWNERS
  8. PREUPLOAD.cfg