Avoid duplicate GV lookup for barewords

Avoid duplicate GV lookup for barewords

Since commit f74617600 (5.12), the GV lookup that this commit removes
from yylex has only been used to see whether the bareword could be a
filehandle.  The result is used by intuit_method to decide whether we
have a method call for ‘foo bar’ or ‘foo $bar’.

Doing this lookup for every bareword we encounter even when we are not
going to call intuit_method is wasteful.

The previous commit ensured that intuit_method is called only once
for each bareword, so we can put that gv lookup directly inside
intuit_method.