C++20 introduced a new overload of std::ostringstream::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.
It also removes a helper function `inet_addr_type_impl::to_sstring()` - it was used only in two places. It was replaced with `fmt::to_string()`.
Closesscylladb/scylladb#16991
* github.com:scylladb/scylladb:
use fmt::to_string() for seastar::net::inet_address
types/types.cc: move stringstream content instead of copying it
53a11cba62