aconfig: first iteration of Rust codegen

Add a new `create-rust-lib` command to generate Rust code. The output is
a src/lib.rs file; the build system is assumed to set the generated
crate's name.

For READ_ONLY flags, the generated code returns a hard-coded true or false.

For READ_WRITE flags, the generated code reaches out to DeviceConfig via
the cc_library server_configurable_flags via the
libprofcollect_libflags_rust Rust bindings. The build system is assumed
to add this to the generated crate's dependencies.

Note: libprofcollect_libflags_rust seems generic enough that it should
be moved to an official Rust wrapper for server_configurable_flags. This
is tracked in b/284096062.

Summary of module the built system is assumed to wrap the auto-generated
code in:

  rust_library {
      name: "lib<namespace>_rs",
      crate_name: "<namespace>_rs",
      edition: "2021",
      clippy_lints: "none",
      no_stdlibs: true,
      lints: "none",
      srcs: ["src/lib.rs"],
      rustlibs: [
          "libprofcollect_libflags_rust",
      ],
  }

Also add a set of test input to be used in the unit tests for a more
coherent test strategy. A follow-up CL will migrate the code in
commands.rs, codegen_java.rs and codegen_cpp.rs.

Bug: 279483360
Bug: 283907905
Test: atest aconfig.test
Test: manual: create cache from files in testdata, create rust lib, add to module template above, verify the module builds
Change-Id: I02606aa3686eda921116e33f7e2df8fd1156a7aa
7 files changed
tree: 3678f45965520eafde2e0bc7c072cd1112c156d3
  1. common/
  2. core/
  3. packaging/
  4. target/
  5. tests/
  6. tools/
  7. .gitignore
  8. banchanHelp.sh
  9. buildspec.mk.default
  10. Changes.md
  11. CleanSpec.mk
  12. Deprecation.md
  13. envsetup.sh
  14. help.sh
  15. METADATA
  16. navbar.md
  17. OWNERS
  18. PREUPLOAD.cfg
  19. rbesetup.sh
  20. README.md
  21. shell_utils.sh
  22. tapasHelp.sh
  23. Usage.txt
README.md

Android Make Build System

This is the Makefile-based portion of the Android Build System.

For documentation on how to run a build, see Usage.txt

For a list of behavioral changes useful for Android.mk writers see Changes.md

For an outdated reference on Android.mk files, see build-system.html. Our Android.mk files look similar, but are entirely different from the Android.mk files used by the NDK build system. When searching for documentation elsewhere, ensure that it is for the platform build system -- most are not.

This Makefile-based system is in the process of being replaced with Soong, a new build system written in Go. During the transition, all of these makefiles are read by Kati, and generate a ninja file instead of being executed directly. That's combined with a ninja file read by Soong so that the build graph of the two systems can be combined and run as one.