Setting a callback with sentry_options_set_before_send does not fire under Windows

[Rubonnek]

I'm currently using the before-send callback under Linux to do my own crash post-processing, but this before_send callback does not fire under Windows.

[Swatinem]

This is a known issue, as on windows we use crashpad which is out-of-process, and does its own sending, which is independent of our whole transport mechanism.

We would need to do more research into figuring out how to actually send everything through our own infrastructure on next startup. But its not really high priority ATM.

[daxpedda]

Considering that we now merged the breakpad and inproc backend for windows, I was trying it out now, without avail.
So I tried on Linux, which also doesn't work.

OS: Windows 10, Version 1809
CMake: 3.17.2
Compiler: MSVC 2019, 16.6.2
Backend: crashpad, inproc
Commit: e966dd1

OS: Ubuntu 18.04.4 LTS
CMake: 3.17.3
Compiler: gcc 9.3.0
Backend: breakpad
Commit: e966dd1

[daxpedda]

I just tried it with e45af98 and it works even with crashpad on windows now.

[Swatinem]

Either way, another thing we do need tests for ;-)