perlfunc: Correct note about eval in DB package

perlfunc: Correct note about eval in DB package

It’s where the subroutine is defined, not the current package,
that matters.

#!perl -l
sub { my $x = 3; foo(); print $x }->();
sub foo { package DB; eval q"$x = 42" }
__END__
3

#!perl -l
sub { my $x = 3; DB::foo(); print $x }->();
package DB;
sub foo { package main; eval q"$x = 42"; }
__END__
42