Create a new modifiable buffer that represents the given POD vector.
template< typename PodType, typename Allocator> mutable_buffers_1 buffer( std::vector< PodType, Allocator > & data, std::size_t max_size_in_bytes);
A mutable_buffers_1 value equivalent to:
mutable_buffers_1( data.size() ? &data : 0, min(data.size() * sizeof(PodType), max_size_in_bytes));
The buffer is invalidated by any vector operation that would also invalidate iterators.