ART: Add GetClassSignature

Add support to retrieve the signature of a JNI class.

Add a test.

Bug: 31684578
Test: m test-art-host-run-test-912-classes
Change-Id: I1cf946996f9089cb5d41e93b4f1064193e9d6350
diff --git a/runtime/openjdkjvmti/Android.bp b/runtime/openjdkjvmti/Android.bp
index 8b6a8f9..5095cfd 100644
--- a/runtime/openjdkjvmti/Android.bp
+++ b/runtime/openjdkjvmti/Android.bp
@@ -21,6 +21,7 @@
            "heap.cc",
            "object_tagging.cc",
            "OpenjdkJvmTi.cc",
+           "ti_class.cc",
            "ti_method.cc",
            "ti_stack.cc",
            "transform.cc"],