Compile standalone system server jars.

This CL updates odrefresh to take an additional environment variable
`STANDALONE_SYSTEMSERVER_JARS` and compile standalone system server jars
accordingly.

Bug: 203198541
Test: atest odsign_e2e_tests
Test: atest art_standalone_odrefresh_tests
Test: atest art_standalone_artd_tests
Test: manual -
  1. Patch aosp/1874113, aosp/1876173, aosp/1875774 and aosp/1875775.
  2. Build a new system image and flash it to a device.
  3. adb logcat odrefresh:D odsign:D "*:S"
  4. See standalone system server jars being compiled and signed.

Change-Id: Ic824c7380cf9530437bc2a95b9ff816a63b22013
diff --git a/artd/libdexopt_test.cc b/artd/libdexopt_test.cc
index 7536dcd..e73c5d6 100644
--- a/artd/libdexopt_test.cc
+++ b/artd/libdexopt_test.cc
@@ -270,7 +270,7 @@
         Contains("--compiler-filter=verify")));
   }
 
-  // Test classloader context
+  // Test empty classloader context
   {
     auto args = default_system_server_args_;
     args.classloaderFds = {};
@@ -281,6 +281,15 @@
         Not(Contains(HasSubstr("--class-loader-context-fds"))),
         Contains("--class-loader-context=PCL[]")));
   }
+
+  // Test classloader context as parent
+  {
+    auto args = default_system_server_args_;
+    args.classloaderContextAsParent = true;
+    std::vector<std::string> cmdline = Dex2oatArgsFromSystemServerArgs(args);
+
+    EXPECT_THAT(cmdline, Contains("--class-loader-context=PCL[];PCL[/cl/abc.jar:/cl/def.jar]"));
+  }
 }
 
 TEST_F(LibDexoptTest, AddDex2oatArgsFromSystemServerArgs_InvalidArguments) {