ART: Clean up art_field.h

Clean up the header. Fix up other headers including the -inl file,
in an effort to prune the include graph. Fix broken transitive
includes by making includes explicit.

Test: m
Change-Id: I6ff2d6f89b741d8188e19426eccf4743fec688fc
diff --git a/runtime/entrypoints/entrypoint_utils-inl.h b/runtime/entrypoints/entrypoint_utils-inl.h
index caf2e5d..e03ca79 100644
--- a/runtime/entrypoints/entrypoint_utils-inl.h
+++ b/runtime/entrypoints/entrypoint_utils-inl.h
@@ -39,6 +39,7 @@
 #include "runtime.h"
 #include "stack_map.h"
 #include "thread.h"
+#include "well_known_classes.h"
 
 namespace art {