After a0f12a0258e4020bd657ee80b7d8f22bd33ea223 NODE_GASGN and
NODE_GVAR hold same value on both nd_vid and nd_entry.
This commit stops setting value to nd_entry and makes to use only
nd_vid.

Since [Misc #19679] migrated the wiki, these links should be updated
to their new locations.

This works like:

```
(gdb) cfp
CFP (count=3, addr=0x7ffff73fef50):
$1 = {pc = 0x555556bf7818, sp = 0x7ffff72ff078, iseq = 0x7ffff2603270, self = 140737344619296, ep = 0x7ffff72ff058, block_code = 0x0,
  __bp__ = 0x7ffff72ff060, jit_return = 0x555558c2b000}

Stack (size=3):
[0] FIXNUM: 1
[1] T_STRING: "" bytesize:0 (embed) encoding:1 coderange:7bit $2 = (struct RString *) 0x7ffff249ea80
[2] [PROMOTED] T_OBJECT: $3 = {flags = 21474844769, klass = 140737344040416}
$4 = {0x24, 0x24, 0x24}

(gdb) cfp + 1
CFP (count=3, addr=0x7ffff73fef90):
$5 = {pc = 0x5555567a78f8, sp = 0x7ffff72ff040, iseq = 0x7ffff26032d0, self = 140737344619296, ep = 0x7ffff72ff038, block_code = 0x0,
  __bp__ = 0x7ffff72ff040, jit_return = 0x555558c2b000}

Stack (size=0):
```

It was crashing with:
No symbol "ROBJECT_EMBED_LEN_MAX" in current context.

Warning: 'set logging on', an alias for the command 'set logging enabled', is deprecated.
Use 'set logging enabled on'.

Other changes are needed to bring .gdbinit up-to-date with current ruby.
It looks like lldb is the preferred approach now, and that config *is*
being kept up-to-date.  Still, this might be helpful to someone?

Now that RUBY_FL_TAINT is recycled to become new RUBY_FL_SHAREABLE.
Setting/clearing this flag from extension libraries break Ractor.
Especially problematic one is OBJ_INFECT, which would make non-shareable
objects travel across Ractor boundaries.

Such operations should just be prohibited.