xgettext: Perl: Avoid unbounded nesting_depth growth, part 4.

xgettext: Perl: Avoid unbounded nesting_depth growth, part 4.

* gettext-tools/src/x-perl.c: Improve parsing of array dereferences.
(extract_variable): After parsing a braced {variable_name}, increment
varbody_length, so as to not parse the following character. If this character
is a closing parenthesis, is would disturb the enclosing extract_balanced call.

Test case:
==========================================
sub in_multi_expanded($)
{
  if (@{$self}) {
  }
}
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