[networking.ts] DynamicBuffer prepare exception specification

Submitter: Vinnie Falco

The current wording for the DynamicBuffer prepare member function implies that std::length_error is the only allowable thrown exception. This should be changed to reflect that any exception may be thrown, with std::length_error thrown in particular when size() + n exceeds max_size().

Proposed resolution:

This wording is relative to N4695.

1. Modify 16.2.4 [buffer.reqmts.dynamicbuffer], table 14, row 6 as indicated:

   Throws: length_error if size() + n exceeds max_size() or any other exception if the request cannot otherwise be satisfied.