Update current namespace management by using control frames and lexical contexts

to fix inconsistent and wrong current namespace detections.

This includes:
* Moving load_path and related things from rb_vm_t to rb_namespace_t to simplify
  accessing those values via namespace (instead of accessing either vm or ns)
* Initializing root_namespace earlier and consolidate builtin_namespace into root_namespace
* Adding VM_FRAME_FLAG_NS_REQUIRE for checkpoints to detect a namespace to load/require files
* Removing implicit refinements in the root namespace which was used to determine
  the namespace to be loaded (replaced by VM_FRAME_FLAG_NS_REQUIRE)
* Removing namespaces from rb_proc_t because its namespace can be identified by lexical context
* Starting to use ep[VM_ENV_DATA_INDEX_SPECVAL] to store the current namespace when
  the frame type is MAGIC_TOP or MAGIC_CLASS (block handlers don't exist in this case)

1 files changed, 1 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index 019a2d19a2..0ff59efd98 100644
--- a/eval.c
+++ b/eval.c
@@ -80,6 +80,7 @@ ruby_setup(void)
     rb_vm_encoded_insn_data_table_init();
     Init_enable_namespace();
     Init_vm_objects();
+    Init_root_namespace();
     Init_fstring_table();
 
     EC_PUSH_TAG(GET_EC());