rv2cv hooks should not create 2nd-class subs

rv2cv hooks should not create 2nd-class subs

$ perl5.17.2 -Mblib -e 'sub foo{}; foo $bar; use Lexical::Sub baz => sub{}; baz $bar'
Can't call method "baz" on an undefined value at -e line 1.
$ perl5.17.2 -Mblib -e 'sub foo{}; foo bar; use Lexical::Sub baz => sub{}; baz bar'
Can't locate object method "baz" via package "bar" (perhaps you forgot to load "bar"?) at -e line 1.

So if you use Lexical::Sub, your sub doesn’t get to participate in
determining whether ‘foo $bar’ or ‘foo bar’ is a method call.

This is because Lexical::Sub uses an rv2cv hook to intercept sub
lookup.  And toke.c:S_intuit_method thinks there cannot be a CV with-
out a GV (which was the case when it was first written).

Commit f7461760 introduced this rv2cv hooking for bareword lookup, but
failed to update S_intuit_method accordingly.