=head2 qw(...) can no longer be used as parentheses

C<qw> lists used to fool the parser into thinking they were always
surrounded by parentheses.  This permitted some surprising constructions
such as C<foreach $x qw(a b c) {...}>, which should really be written
C<foreach $x (qw(a b c)) {...}>.  These would sometimes get the lexer into
the wrong state, so they didn't fully work, and the similar C<foreach qw(a
b c) {...}> that one might expect to be permitted never worked at all.

This side effect of C<qw> has now been abolished.  It has been deprecated
since Perl v5.13.11.  It is now necessary to use real parentheses
everywhere that the grammar calls for them.