ART: Clean up #includes in jit_code_cache.h .

And fix code that relied on those indirect #includes.

Also remove forward declaration of art::LinkerPatch because
we actually use art::linker::LinkerPatch.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 65574695
Change-Id: I102affed9a3eacbd21b79c370fbc72b5fc762c96
diff --git a/test/566-polymorphic-inlining/polymorphic_inline.cc b/test/566-polymorphic-inlining/polymorphic_inline.cc
index b75becf..e2b8aa0 100644
--- a/test/566-polymorphic-inlining/polymorphic_inline.cc
+++ b/test/566-polymorphic-inlining/polymorphic_inline.cc
@@ -19,6 +19,7 @@
 #include "jit/jit.h"
 #include "jit/jit_code_cache.h"
 #include "jit/profiling_info.h"
+#include "mirror/class.h"
 #include "oat_quick_method_header.h"
 #include "scoped_thread_state_change-inl.h"
 #include "stack_map.h"