Split /system and /vendor modules, allow multi-installation

Nothing changes if BOARD_VNDK_VERSION isn't set.

When the VNDK is enabled (BOARD_VNDK_VERSION in Make), this will split
/system and /vendor modules into two different variant spaces that can't
link to each other. There are a few interfaces between the two variant
spaces:

The `llndk_library` stubs will be available in the /vendor variant, but
won't be installed, so at runtime the /system variant will be used.

Setting `vendor_available: true` will split a module into both variants.
The /system (or "core") variant will compile just like today. The
/vendor ("vendor") variant will compile against everything else in the
vendor space (so LL-NDK instead of libc/liblog/etc). There will be two
copies of these libraries installed onto the final device.

Since the available runtime interfaces for vendor modules may be
reduced, and your dependencies may not expose their private interfaces,
we allow the vendor variants to reduce their compilation set, and export
a different set of headers:

  cc_library {
      name: "libfoo",
      srcs: ["common.cpp", "private_impl.cpp"],
      export_include_dirs: ["include"],
      target: {
          vendor: {
	      export_include_dirs: ["include_vndk"],
	      exclude_srcs: ["private_impl.cpp"],
	      srcs: ["vendor_only.cpp"],
	  },
      },
  }

So the "core" variant would compile with both "common.cpp" and
"private_impl.cpp", and export "include".

The "vendor" variant would compile "common.cpp" and "vendor_only.cpp",
and export "include_vndk".

Bug: 36426473
Bug: 36079834
Test: out/soong/build.ninja, out/soong/Android- only changes due to _core addition and
      .llndk -> .vendor
Test: attempt to compile with BOARD_VNDK_VERSION:=current
Change-Id: Idef28764043bf6c33dc0d2e7e2026c38867ff769

1 files changed, 2 insertions, 0 deletions

diff --git a/Android.bp b/Android.bp
index 0e3ac02f..2ae993f7 100644
--- a/Android.bp
+++ b/Android.bp
@@ -232,6 +232,7 @@ cc_defaults {
 toolchain_library {
     name: "libatomic",
     defaults: ["linux_bionic_supported"],
+    vendor_available: true,
     arch: {
         arm: {
             instruction_set: "arm",
@@ -242,6 +243,7 @@ toolchain_library {
 toolchain_library {
     name: "libgcc",
     defaults: ["linux_bionic_supported"],
+    vendor_available: true,
     arch: {
         arm: {
             instruction_set: "arm",