[perl #3112] Stop last from returning values

[perl #3112] Stop last from returning values

In push @a, last, it can try to return the @a, copying it like a sca-
lar in the process, resulting in Bizarre copy of ARRAY in last.

In do{{&{sub{"Just another Perl hacker,\n"}},last}}, it returns "Just
another Perl hacker,\n".

The former is clearly a bug.  The latter depends on a side-effect of
the same bug.

‘last’ really should not be trying to return the values that the same
statement has accumulated so far.