Fix buildbots hidden_api_test

Target buildbots set /system to be the runtime module root because they
are running without an apex. The test assumes that /system dex files are assigned
to the application domain but here they get assigned to the core-platform domain.

Adjust the domain setting logic to check if the runtime module root is
distict from the android root (as a proxy for 'is running with apex').
If not (as is the case with the buildbots), skip checks against apex
locations.

Test: m test-art-target-gtest-hidden_api_test
Change-Id: Iff3890ec69cb04a1e4ed5bc2a3b5c652ada05f36
diff --git a/runtime/hidden_api.cc b/runtime/hidden_api.cc
index 23e2e1f..4ef3842 100644
--- a/runtime/hidden_api.cc
+++ b/runtime/hidden_api.cc
@@ -76,20 +76,23 @@
 static Domain DetermineDomainFromPath_Impl(const std::string& path,
                                            const std::string& dex_location,
                                            ObjPtr<mirror::ClassLoader> class_loader) {
-  // We check /system/framework before the runtime module location, because the
-  // runtime module location in a testing environment could be /system.
+  // If running with APEX, check `path` against known APEX locations.
+  // These checks will be skipped on target buildbots where ANDROID_RUNTIME_ROOT
+  // is set to "/system".
+  if (RuntimeModuleRootDistinctFromAndroidRoot()) {
+    if (LocationIsOnRuntimeModule(path.c_str()) || LocationIsOnConscryptModule(path.c_str())) {
+      return Domain::kCorePlatform;
+    }
+
+    if (LocationIsOnApex(path.c_str())) {
+      return Domain::kPlatform;
+    }
+  }
+
   if (LocationIsOnSystemFramework(path.c_str())) {
     return Domain::kPlatform;
   }
 
-  if (LocationIsOnRuntimeModule(path.c_str()) || LocationIsOnConscryptModule(path.c_str())) {
-    return Domain::kCorePlatform;
-  }
-
-  if (LocationIsOnApex(path.c_str())) {
-    return Domain::kPlatform;
-  }
-
   if (class_loader.IsNull()) {
     LOG(WARNING) << "DexFile " << dex_location
         << " is in boot class path but its path " << path << " is not in a known location";