Fix documentation of QStringTokenizer

qstringtokenizer.cpp:156: (qdoc) warning: Cannot find 'QStringTokenizer::difference_type' specified with '\typedef' in any header file
qstringtokenizer.cpp:162: (qdoc) warning: Cannot find 'QStringTokenizer::size_type' specified with '\typedef' in any header file
qstringtokenizer.cpp:168: (qdoc) warning: Cannot find 'QStringTokenizer::reference' specified with '\typedef' in any header file
qstringtokenizer.cpp:177: (qdoc) warning: Cannot find 'QStringTokenizer::const_reference' specified with '\typedef' in any header file
qstringtokenizer.cpp:183: (qdoc) warning: Cannot find 'QStringTokenizer::pointer' specified with '\typedef' in any header file
qstringtokenizer.cpp:192: (qdoc) warning: Cannot find 'QStringTokenizer::const_pointer' specified with '\typedef' in any header file
qstringtokenizer.cpp:198: (qdoc) warning: Cannot find 'QStringTokenizer::iterator' specified with '\typedef' in any header file
qstringtokenizer.cpp:210: (qdoc) warning: Cannot find 'QStringTokenizer::const_iterator' specified with '\typedef' in any header file
qstringtokenizer.cpp:219: (qdoc) warning: Cannot find 'QStringTokenizer::sentinel' specified with '\typedef' in any header file
qstringtokenizer.cpp:228: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer(Haystack haystack, String needle, Qt::CaseSensitivity cs, Qt::SplitBehavior sb)
    error: unknown type name 'Haystack'
    error: unknown type name 'String'
    error: deduction guide declaration without trailing return type
    error: deduction guide cannot have a function definition
qstringtokenizer.cpp:228: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer(Haystack haystack, String needle, Qt::SplitBehavior sb, Qt::CaseSensitivity cs)
    error: unknown type name 'Haystack'
    error: unknown type name 'String'
    error: deduction guide declaration without trailing return type
    error: deduction guide cannot have a function definition
qstringtokenizer.cpp:247: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer::const_iterator QStringTokenizer::begin() const
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
qstringtokenizer.cpp:256: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer::const_iterator QStringTokenizer::cbegin() const
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
qstringtokenizer.cpp:264: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer::sentinel QStringTokenizer::end() const
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
qstringtokenizer.cpp:273: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer::sentinel QStringTokenizer::cend() const
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
qstringtokenizer.cpp:281: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer::toContainer(Container &&c) const &
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
    error: unknown type name 'Container'
qstringtokenizer.cpp:313: (qdoc) warning: clang found diagnostics parsing \fn QStringTokenizer::toContainer(Container &&c) const &&
    error: 'QStringTokenizer' is not a class, namespace, or enumeration
    error: unknown type name 'Container'
qstringtokenizer.cpp:346: (qdoc) warning: clang found diagnostics parsing \fn qTokenize(Haystack &&haystack, Needle &&needle, Flags...flags)
    error: unknown type name 'Haystack'
    error: unknown type name 'Needle'
    error: unknown type name 'Flags'
    error: type 'int' of function parameter pack does not contain any unexpanded parameter packs
    error: C++ requires a type specifier for all declarations
qstringtokenizer.cpp:45: (qdoc) warning: Can't link to 'index.html'
qstringtokenizer.cpp:45: (qdoc) warning: '\brief' statement does not end with a full stop.
qstringtokenizer.cpp:45: (qdoc) warning: Can't link to 'index.html'
qstringtokenizer.cpp:45: (qdoc) warning: Can't link to 'reentrant'
qstringtokenizer.cpp:45: (qdoc) warning: Can't link to 'QLatin1Sting::split()'