Merge remote-tracking branch 'goog/androidx-platform-dev' into master
* goog/androidx-platform-dev:
Pull upstream changes.
Pull upstream changes.
Move compilation of libicing.so into appsearch:appsearch.
Move icing lib build.gradle to root of repo.
Build the external/icing project in a self-contained manner.
Hide classes from public API surface.
Pull upstream changes.
Uncomment CMakeLists.txt to start building icing native lib.
Update from upstream, including proto location changes.
Copy over changes made to Google3 codebase in Icing.
Update CMakeLists.txt to use precompiled protoc.
Modify external/icing CMake to build against libandroidicu.
Pull upstream changes.
Use add_custom_command instead of execute_process for building protos.
Implement jarjar for icing protos.
Split icing project into two parts: protos/java, and native lib.
Modify external/icing CMake to link against libprotobuf.
Copy over changes made to Google3 codebase in Icing.
Test: m -j
Change-Id: I69b719ca9b0ca9032eaca5ba23c62dfa03b185f8