LLNDK can re-export headers

Added export_llndk_headers properties to llndk_library module. And a new
module type llndk_headers is added. This is to enable an LLNDK library
to reexport other LLNDK headers.

Bug: 65395259
Test: do the following
// frameworks/native/libs/arect/Android.bp
llndk_headers {
    name: "libarect_vendor_headers",
    export_include_dirs: ["include"],
}

// frameworks/native/libs/nativewindow/Android.bp
llndk_library {
    name: "libnativewindow",
    ....
    export_llndk_headers: ["libarect_vendor_headers"],
}

check that
-Iframeworks/native/libs/arect/include is in LOCAL_EXPORT_CFLAGS of
libnativewindow.vendor in out/soong/Android-<product>.mk

Change-Id: If1650414b2967f2042f4ebe2b593ed3f3ea45d3a

cc/cc.go

@@ -1402,6 +1402,9 @@ func vendorMutator(mctx android.BottomUpMutatorContext) {
 		// LL-NDK stubs only exist in the vendor variant, since the
 		// real libraries will be used in the core variant.
 		mctx.CreateVariations(vendorMode)
+	} else if _, ok := m.linker.(*llndkHeadersDecorator); ok {
+		// ... and LL-NDK headers as well
+		mctx.CreateVariations(vendorMode)
 	} else if m.hasVendorVariant() {
 		// This will be available in both /system and /vendor
 		// or a /system directory that is available to vendor.

cc/llndk_library.go

@@ -23,6 +23,7 @@ import (
 
 var (
 	llndkLibrarySuffix = ".llndk"
+	llndkHeadersSuffix = ".llndk"
 )
 
 // Creates a stub shared library based on the provided version file.
@@ -55,6 +56,9 @@ type llndkLibraryProperties struct {
 	// When set to false, this module can only be depended on by VNDK libraries, not vendor
 	// libraries. This effectively hides this module from vendors. Default value is true.
 	Vendor_available bool
+
+	// list of llndk headers to re-export include directories from.
+	Export_llndk_headers []string `android:"arch_variant"`
 }
 
 type llndkStubDecorator struct {
@@ -78,7 +82,10 @@ func (stub *llndkStubDecorator) compile(ctx ModuleContext, flags Flags, deps Pat
 }
 
 func (stub *llndkStubDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
-	return Deps{}
+	headers := addSuffix(stub.Properties.Export_llndk_headers, llndkHeadersSuffix)
+	deps.HeaderLibs = append(deps.HeaderLibs, headers...)
+	deps.ReexportHeaderLibHeaders = append(deps.ReexportHeaderLibHeaders, headers...)
+	return deps
 }
 
 func (stub *llndkStubDecorator) Name(name string) string {
@@ -173,6 +180,35 @@ func llndkLibraryFactory() android.Module {
 	return module
 }
 
+type llndkHeadersDecorator struct {
+	*libraryDecorator
+}
+
+func (headers *llndkHeadersDecorator) Name(name string) string {
+	return name + llndkHeadersSuffix
+}
+
+func llndkHeadersFactory() android.Module {
+	module, library := NewLibrary(android.DeviceSupported)
+	library.HeaderOnly()
+	library.setStatic()
+
+	decorator := &llndkHeadersDecorator{
+		libraryDecorator: library,
+	}
+
+	module.compiler = nil
+	module.linker = decorator
+	module.installer = nil
+
+	module.AddProperties(&library.MutatedProperties, &library.flagExporter.Properties)
+
+	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibBoth)
+
+	return module
+}
+
 func init() {
 	android.RegisterModuleType("llndk_library", llndkLibraryFactory)
+	android.RegisterModuleType("llndk_headers", llndkHeadersFactory)
 }