C++20 introduced a new overload of std::ofstringstream::str()
that is selected when the mentioned member function is called
on r-value.
The new overload returns a string, that is move-constructed
from the underlying string instead of being copy-constructed.
This change applies std::move() on stringstream objects before
calling str() member function to avoid copying of the underlying
buffer.
Signed-off-by: Patryk Wrobel <patryk.wrobel@scylladb.com>
Closesscylladb/scylladb#16990