Multi client socket connections allow multiple clients to request crash
dumps from a handler process using a single, shared socket connection.
This connection mode does not support using a broker process which
requires a dedicated socket connection to ensure handler messages
aren't intercepted by the wrong clients.
The handler uses SIGCONT to indicate to the crasher when a crash dump
is complete (or has failed) and may continue.
Bug: crashpad:284
Change-Id: I2031029cd254f17497cbf7e7d8740c289581e8aa
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/1559306
Reviewed-by: Mark Mentovai <mark@chromium.org>