Annotate dependency tags for dependencies of installed files

Relands Ic22603a5c0718b5a21686672a7471f952b4d1017 with a minor
change to track libc++ dependencies for python hosts and after
a fix to an internal genrule that depended on transitively
installed java libraries (ag/13068670).

Soong currently assumes that installed files should depend on
installed files of all transitive dependencies, which results
in extra installed file dependencies through genrules, static
libs, etc.

Annotate dependency tags for dependencies for which the
installed files are necessary such as shared libraries
and JNI libraries.

This avoids extra installed files, and is also a first step
towards genrules using their own copy of tools instead of
the installed copy.

Bug: 124313442
Test: m checkbuild
Test: java.TestBinary
Test: cc.TestInstallSharedLibs
Test: deptag_test.go
Change-Id: I725871249d561428e6f67bba6a7c65b580012b72

android/deptag.go

@@ -0,0 +1,45 @@
+// Copyright 2020 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 android
+
+import "github.com/google/blueprint"
+
+// Dependency tags can implement this interface and return true from InstallDepNeeded to annotate
+// that the installed files of the parent should depend on the installed files of the child.
+type InstallNeededDependencyTag interface {
+	// If InstallDepNeeded returns true then the installed files of the parent will depend on the
+	// installed files of the child.
+	InstallDepNeeded() bool
+}
+
+// Dependency tags can embed this struct to annotate that the installed files of the parent should
+// depend on the installed files of the child.
+type InstallAlwaysNeededDependencyTag struct{}
+
+func (i InstallAlwaysNeededDependencyTag) InstallDepNeeded() bool {
+	return true
+}
+
+var _ InstallNeededDependencyTag = InstallAlwaysNeededDependencyTag{}
+
+// IsInstallDepNeeded returns true if the dependency tag implements the InstallNeededDependencyTag
+// interface and the InstallDepNeeded returns true, meaning that the installed files of the parent
+// should depend on the installed files of the child.
+func IsInstallDepNeeded(tag blueprint.DependencyTag) bool {
+	if i, ok := tag.(InstallNeededDependencyTag); ok {
+		return i.InstallDepNeeded()
+	}
+	return false
+}