add "EXTERNAL" as special value of LOCAL_CERTIFICATE

Setting LOCAL_CERTIFICATE to "EXTERNAL" now marks an apk (either a
prebuilt or otherwise) as needing the default test key within the
system, but one that should be signed after the target_files is
produced but before sign_target_files_apks does the rest of the
signing.  (We use this to ship apps on the system that are signed by
third parties, like Facebook.)
6 files changed
tree: 26993d68c40ee81a4a727631bb5bc23cb744e35a
  1. core/
  2. libs/
  3. target/
  4. tools/
  5. buildspec.mk.default
  6. cleanspec.mk
  7. envsetup.sh