Prevent sdk variants from install

Platform variants should be available even when unbundled_build so that
unbundled build of com.android.virt apex can correctly have microdroid
image with system variants.

Bug: 268582372
Test: m (soong test)
Test: banchan com.android.virt aosp_arm64
      UNBUNDLED_BUILD_SDKS_FROM_SOURCE=true m apps_only dist
      (microdroid should have the same contents)
Change-Id: I682e4f1f477f3024f7719dfaa67006ef335e0640

filesystem/filesystem_test.go

@@ -188,3 +188,40 @@ func TestAvbAddHashFooter(t *testing.T) {
 	android.AssertStringDoesContain(t, "Can't find --include_descriptors_from_image",
 		cmd, "--include_descriptors_from_image ")
 }
+
+func TestFileSystemShouldInstallCoreVariantIfTargetBuildAppsIsSet(t *testing.T) {
+	context := android.GroupFixturePreparers(
+		fixture,
+		android.FixtureModifyProductVariables(func(variables android.FixtureProductVariables) {
+			variables.Unbundled_build_apps = []string{"bar"}
+		}),
+	)
+	result := context.RunTestWithBp(t, `
+		android_system_image {
+			name: "myfilesystem",
+			deps: [
+				"libfoo",
+			],
+			linker_config_src: "linker.config.json",
+		}
+
+		cc_library {
+			name: "libfoo",
+			shared_libs: [
+				"libbar",
+			],
+			stl: "none",
+		}
+
+		cc_library {
+			name: "libbar",
+			sdk_version: "9",
+			stl: "none",
+		}
+	`)
+
+	inputs := result.ModuleForTests("myfilesystem", "android_common").Output("deps.zip").Implicits
+	android.AssertStringListContains(t, "filesystem should have libbar even for unbundled build",
+		inputs.Strings(),
+		"out/soong/.intermediates/libbar/android_arm64_armv8-a_shared/libbar.so")
+}