feature/android updated (48b5a770f24 -> 468e8d7322e)

[Po Lu]

oldosfan pushed a change to branch feature/android.

      from  48b5a770f24 Fix visiting and saving writable content provider files
       new  d8ea139e83d Improve ndk-build implementation
       new  468e8d7322e ; * cross/ndk-build/README: Update accordingly.


Summary of changes:
 build-aux/ndk-build-helper.mk |  10 +--
 cross/ndk-build/README        |   1 +
 m4/ndk-build.m4               | 185 +++++++++++++++++++-----------------------
 3 files changed, 88 insertions(+), 108 deletions(-)