Revision 571893

Removed hundred of assignments of an empty list or hash to a
just created empty array or hash. Explanation: operator 'my' brings
to life scalars with an undefined value, lists with no elements,
and hashes with no keys. The following assignments are thus redundant:
my $x=undef; my @x=(); my %x=();  Interestingly noone does the first,
but there were about 100 cases of second and third. Even as a stylistic
measure I don't think it counts, as it was not used systematically,
and only in minority of cases.