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/openjdkjvmti/ti_stack.cc b/openjdkjvmti/ti_stack.cc
index 4a3eac8..385ac45 100644
--- a/openjdkjvmti/ti_stack.cc
+++ b/openjdkjvmti/ti_stack.cc
@@ -36,6 +36,7 @@
 #include <unordered_map>
 #include <vector>
 
+#include "arch/context.h"
 #include "art_field-inl.h"
 #include "art_method-inl.h"
 #include "art_jvmti.h"