[lldb] Correct false case in SwiftOptionalSummaryProvider::DoesPrintChildren

[kastiglione]

Return false from DoesPrintChildren for .none values.

From the docstring for ExtractSomeIfAny:

/// Returns {} on error, nullptr on .none, and a ValueObject on .some.

This changes the case where nullptr is returned, indicating .none. In those cases, children should not be printed.

I have seen an issue in the wild where "nil" is printed as the summary, yet children are incorrectly printed. I have not yet figured out a reproduction. An example output is:

headKeyView = nil {
  NSResponder = <parent failed to evaluate: read memory from 0x0 failed (0 of 8 bytes read)>
  _frame = <parent failed to evaluate: read memory from 0x0 failed (0 of 8 bytes read)>
  _bounds = <parent failed to evaluate: read memory from 0x0 failed (0 of 8 bytes read)>
  _subviews = <parent failed to evaluate: read memory from 0x0 failed (0 of 8 bytes read)>
  ...
}

[kastiglione]

@swift-ci test

[kastiglione]

@swift-ci test

[kastiglione]

@swift-ci test windows