Fix: compilation failed on gcc 10.2 due to missing include. (#11300)

'_exit' is defined in 'unistd.h'.

Add: use breakpad to create crash.dmp on MacOS / Linux too (#11202)

Normally only the Windows platform could create a crash.dmp, making
analysing crash-reports from MacOS / Linux rather tricky.

Remove: last remnants of SunOS (#11210)

We have no evidence SunOS has been tried in the last few years,
and the code is awkward enough to just remove.

Codechange: Remove duplicated includes. (#10888)

These are now included by stdafx.h so don't need to be included again.

Codechange: Place gamelog into its own class, along with internal data.

Data is now stored in vectors to avoid manual memory management and
passing lengths around.

Codechange: Use override specifer for overriding member declarations

This is a C++11 feature that allows the compiler to check that a virtual
member declaration overrides a base-class member with the same signature.

Also src/blitter/32bpp_anim_sse4.hpp +38 is no longer erroneously marked
as virtual despite being a template.