OpenSystemsDevelopment / qpdf

When seeing to a position based on a value read from the input, we are
prone to integer overflow (fuzz issue 15442). Seek in two stages to
move the overflow check into the input source code.

Just because we know an indirect reference is null, doesn't mean we
shouldn't keep it indirect.

For some reason, qpdf from the beginning was replacing indirect
references to null with literal null in arrays even after removing the
old behavior of flattening scalar references. This seems like a bad
idea.

This message used to only appear for PDF >= 1.2. The invalid name is
valid for PDF 1.0 and 1.1. However, since QPDFWriter may write a newer
version, it's better to detect and warn in all cases. Therefore make
the warning more informative.

This change works around STL problems with Embarcadero C++ Builder
version 10.2, but std::vector is more common than std::list in qpdf,
and this is a relatively new API, so an API change is tolerable.

Thanks to Thorsten Schöning <6223655+ams-tschoening@users.noreply.github.com>
for the fix.

There were a few cases that could be caused by invalid input rather
than bugs in the code which were throwing logic_error instead of
runtime_error.

This also reverts the addition of a new checkLinearization that
distinguishes errors from warnings. There's no practical distinction
between what was considered an error and what was considered a
warning.

Thanks to github user zdenop for supplying some additional
error-handling code.

Use PointerHolder in several places where manually memory allocation
and deallocation were being used. This helps to protect against memory
leaks when exceptions are thrown in surprising places.

This code was essentially duplicated between test_driver and
standalone_fuzz_target_runner.

In a small number of cases, it makes sense to replace an overloaded
function with a function that takes a default argument. We can do this
now because we've already broken binary compatibility since the last
release.

Have classes contain only a single private member of type
PointerHolder<Members>. This makes it safe to change the structure of
the Members class without breaking binary compatibility. Many of the
classes already follow this pattern quite successfully. This brings in
the rest of the class that are part of the public API.