Move SingletonTest back to libutils_test

Use the new "data_libs:" to specify test library dependency. This is
like "data:" and it treats compiled libraries as test data files.
The result is libutils_test_singleton{1,2} is picked up by libutils_test
and installed next to the test binary.

Mark the test libs libutils_test_singleton{1,2} as uninstallable. This
prevents installing libutils_test_singleton{1,2} directly and only
permits installing via "data_libs:".

```
$ m libutils_test
testcases
└── libutils_test
    ├── arm
    │   ├── libutils_test
    │   ├── libutils_test_singleton1.so
    │   └── libutils_test_singleton2.so
    ├── arm64
    │   ├── libutils_test
    │   ├── libutils_test_singleton1.so
    │   └── libutils_test_singleton2.so
    └── libutils_test.config
```

Bug: 124838889
Test: atest libutils_test
Change-Id: I432135e128fc9eedb1b8c18a331957e271d8b0f0

libutils/Android.bp

@@ -248,6 +248,7 @@ cc_test {
         "LruCache_test.cpp",
         "Mutex_test.cpp",
         "SharedBuffer_test.cpp",
+        "Singleton_test.cpp",
         "String8_test.cpp",
         "String16_test.cpp",
         "StrongPointer_test.cpp",
@@ -284,6 +285,11 @@ cc_test {
         },
     },
 
+    data_libs: [
+        "libutils_test_singleton1",
+        "libutils_test_singleton2",
+    ],
+
     cflags: [
         "-Wall",
         "-Wextra",
@@ -294,29 +300,10 @@ cc_test {
     test_suites: ["device-tests"],
 }
 
-// TODO: the test infrastructure isn't yet capable of running this,
-// so it's broken out into its own test so that the main libutils_tests
-// can be in presubmit even if this can't.
-
-cc_test {
-    name: "libutils_singleton_test",
-    srcs: ["Singleton_test.cpp"],
-    cflags: [
-        "-Wall",
-        "-Werror",
-    ],
-    shared_libs: ["libbase"],
-
-    required: [
-        ":libutils_test_singleton1",
-        ":libutils_test_singleton2",
-    ],
-}
-
 cc_test_library {
     name: "libutils_test_singleton1",
     host_supported: true,
-    relative_install_path: "libutils_test",
+    installable: false,
     srcs: ["Singleton_test1.cpp"],
     cflags: [
         "-Wall",
@@ -327,7 +314,7 @@ cc_test_library {
 cc_test_library {
     name: "libutils_test_singleton2",
     host_supported: true,
-    relative_install_path: "libutils_test",
+    installable: false,
     srcs: ["Singleton_test2.cpp"],
     cflags: [
         "-Wall",