Inform about System.exit() call in logcat

This diagnostic message helps to filter out crashes during System.exit()
when thread's behaviour is undefined.

Change-Id: I772932a35b503b1efca695e7da7bf2e562c03a7c
Signed-off-by: Dmitry Petrochenko <dmitry.petrochenko@intel.com>
diff --git a/runtime/native/java_lang_Runtime.cc b/runtime/native/java_lang_Runtime.cc
index 496a1b2..fb708a2 100644
--- a/runtime/native/java_lang_Runtime.cc
+++ b/runtime/native/java_lang_Runtime.cc
@@ -38,6 +38,7 @@
 }
 
 static void Runtime_nativeExit(JNIEnv*, jclass, jint status) {
+  LOG(INFO) << "System.exit called, status: " << status;
   Runtime::Current()->CallExitHook(status);
   exit(status);
 }