This gives users of the class easy access to the Prealloc template
argument, without having to write a pattern-matcher like
template <typename T>
constexpr qsizetype preallocated_size_v;
template <typename T, qsizetype N>
constexpr qsizetype preallocated_size_v<QVarLengthArray<T,N>> = N;
first.
[ChangeLog][QtCore][QVarLengthArray] Added PreallocatedSize nested
constant, equal to the Prealloc template argument.
Change-Id: I928eaa5e62967445cdd7b0c2759567483fdb8997
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
af051f9be2