So far, type-name strings for class template instantiations were constructed
in QMetaTypeId::qt_metatype_id() by concatenating various bits and pieces
into a QVarLengthArray<char>, presumably to avoid the dynamic memory
allocation for small strings.
Yet, when passing the result to qRegisterNormalisedMetaType, which takes
a QByteArray, the QVarLengthArray was copied from, not by
QByteArray::fromRawData(), but by QByteArray(const char*,int), which
unconditionally results in a dynamic memory allocation after all.
What's worse: the characters are copied twice: First into the QVarLengthArray,
and then into the QByteArray.
Remove the first of these copies by using QByteArray+reserve() to copy
directly into the final QByteArray.
Change-Id: Id915798a318fe97279a7cc0aca176544f99c7e86
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>