Add header-abi-checker for Vndk abi checks.

header-abi-dumper: dumps abi exported by source files for Vndk.
header-abi-linker: links abi dumps produced by header-abi-dumper.
header-abi-diff: compares linked dumps.

Test: mm -j64 showcommands > make_log in bionic/libc.
      This produced linked dumps in out/soong/.intermediates.
      Copied these dumps to
      prebuilts/abi-dumps/ndk/current/arm64/source-based/.
      Changed the abi and re-ran mm -j64 showcommands > make_log
      confirmed that the build reported compatibility breakge without
      actually failing (advisory mode).

Change-Id: Iccad6908fe68a80f47230751671d156893b96ead

cc/sabi.go

@@ -0,0 +1,63 @@
+// Copyright 2017 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cc
+
+import (
+	"android/soong/android"
+	"github.com/google/blueprint"
+
+	"android/soong/cc/config"
+)
+
+type SAbiProperties struct {
+	CreateSAbiDumps bool `blueprint:"mutated"`
+}
+
+type sabi struct {
+	Properties SAbiProperties
+}
+
+func (sabimod *sabi) props() []interface{} {
+	return []interface{}{&sabimod.Properties}
+}
+
+func (sabimod *sabi) begin(ctx BaseModuleContext) {}
+
+func (sabimod *sabi) deps(ctx BaseModuleContext, deps Deps) Deps {
+	return deps
+}
+
+func (sabimod *sabi) flags(ctx ModuleContext, flags Flags) Flags {
+	return flags
+}
+
+func sabiDepsMutator(mctx android.TopDownMutatorContext) {
+	if c, ok := mctx.Module().(*Module); ok &&
+		((inList(c.Name(), config.VndkLibraries())) || (inList(c.Name(), config.LLndkLibraries())) ||
+			(c.sabi != nil && c.sabi.Properties.CreateSAbiDumps)) {
+		mctx.VisitDirectDeps(func(m blueprint.Module) {
+			tag := mctx.OtherModuleDependencyTag(m)
+			switch tag {
+			case staticDepTag, staticExportDepTag, lateStaticDepTag, wholeStaticDepTag:
+
+				cc, _ := m.(*Module)
+				if cc == nil {
+					return
+				}
+				cc.sabi.Properties.CreateSAbiDumps = true
+			}
+		})
+	}
+}