Releases owenrship of the data and gives it away as
temporary_buffer. This way we can avoid allocation when putting rvalue
sstring if it's already using external storage. Except we need to
allocate a deleter which uses delete[], but this can be fixed later.
It concatenates multiple string-like entities in one go and gives away
an sstring. It does at most one allocation for the final sstring and
one copy per each string. Works with heterogenous arguments, both
sstrings and constant strings are supported, string_views are planned.
It's required for instantiating a sstring with the constructor
basic_sstring(initialized_later, size_t size).
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
