ART: Forward-declare Context

Move deletion to thread.cc, which allows to forward-declare
Context.

Bug: 119869270
Test: mmma art
Change-Id: Ifd9006cd3457d4ab708a289a7f6e1cdf2591c596
diff --git a/test/common/stack_inspect.cc b/test/common/stack_inspect.cc
index 393e773..cb011a8 100644
--- a/test/common/stack_inspect.cc
+++ b/test/common/stack_inspect.cc
@@ -18,6 +18,7 @@
 
 #include <android-base/logging.h>
 
+#include "arch/context.h"
 #include "base/mutex.h"
 #include "dex/dex_file-inl.h"
 #include "jni/jni_internal.h"