Add core-ojtests target to host build and to vogar classpath

This CL adds support of running ojtests (TestNG based) using vogar.
Now run-libcore-tests.sh should be able to run all unit tests including
TestNg ones from upstream.

Bug: 208639267
Test: art/tools/run-libcore-tests.sh --mode host \
      test.java.lang.String.IsBlank
Change-Id: Id842fe5a078b127229380855ce2a60815c560578
diff --git a/tools/run-libcore-tests.py b/tools/run-libcore-tests.py
index 99a6a74..b485c73 100755
--- a/tools/run-libcore-tests.py
+++ b/tools/run-libcore-tests.py
@@ -114,7 +114,7 @@
   "/apex/com.android.conscrypt/javalib/conscrypt.jar",
 ]
 
-CLASSPATH = ["core-tests", "jsr166-tests", "mockito-target"]
+CLASSPATH = ["core-tests", "core-ojtests", "jsr166-tests", "mockito-target"]
 
 def get_jar_filename(classpath):
   base_path = (ANDROID_PRODUCT_OUT + "/../..") if ANDROID_PRODUCT_OUT else "out/target"