Define product_available property

To make a module available to product variants, it must define
`product_available: true`. `vendor_available: true` will not create
product variants any more.
However, in this CL, we don't change the behavior of
`vendor_available` property. It still creates both variants. After we
update all Android.bp files that need to provide product variants
with `product_available: true`, we may upload the remaining patches.

Bug: 150902910
Test: lunch aosp_arm64-userdebug && m
Change-Id: I0fd5be7bbae2c45d5cab3c3c2ca49f53a9b6f975
diff --git a/cc/library.go b/cc/library.go
index d946629..eeddd90 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -72,7 +72,7 @@
 	Suffix *string `android:"arch_variant"`
 
 	Target struct {
-		Vendor struct {
+		Vendor, Product struct {
 			// set suffix of the name of the output
 			Suffix *string `android:"arch_variant"`
 		}
@@ -172,11 +172,11 @@
 	Export_system_include_dirs []string `android:"arch_variant"`
 
 	Target struct {
-		Vendor struct {
+		Vendor, Product struct {
 			// list of exported include directories, like
-			// export_include_dirs, that will be applied to the
-			// vendor variant of this library. This will overwrite
-			// any other declarations.
+			// export_include_dirs, that will be applied to
+			// vendor or product variant of this library.
+			// This will overwrite any other declarations.
 			Override_export_include_dirs []string
 		}
 	}
@@ -253,6 +253,7 @@
 }
 
 func (f *flagExporter) exportedIncludes(ctx ModuleContext) android.Paths {
+	// TODO(b/150902910): product variant must use Target.Product
 	if ctx.useVndk() && f.Properties.Target.Vendor.Override_export_include_dirs != nil {
 		return android.PathsForModuleSrc(ctx, f.Properties.Target.Vendor.Override_export_include_dirs)
 	} else {
@@ -716,6 +717,7 @@
 
 	suffix := ""
 	if useVndk {
+		// TODO(b/150902910): product variant must use Target.Product
 		suffix = String(library.Properties.Target.Vendor.Suffix)
 	}
 	if suffix == "" {
@@ -812,6 +814,7 @@
 		deps.ReexportSharedLibHeaders = append(deps.ReexportSharedLibHeaders, library.SharedProperties.Shared.Export_shared_lib_headers...)
 		deps.ReexportStaticLibHeaders = append(deps.ReexportStaticLibHeaders, library.SharedProperties.Shared.Export_static_lib_headers...)
 	}
+	// TODO(b/150902910): product variant must use Target.Product
 	if ctx.useVndk() {
 		deps.WholeStaticLibs = removeListFromList(deps.WholeStaticLibs, library.baseLinker.Properties.Target.Vendor.Exclude_static_libs)
 		deps.SharedLibs = removeListFromList(deps.SharedLibs, library.baseLinker.Properties.Target.Vendor.Exclude_shared_libs)