Add support for the Nokia N-Gage (#5597)

* Add initial support for the Nokia N-Gage

* N-Gage: disable clipping for the time being, issue needs to be resolved later

* Move va_copy definition to SDL_internal.h

* Move stdlib.h include to SDL_config_ngage.h, much cleaner this way

* Remove redundant include, add HAVE_STDLIB_H

* Revert "N-Gage: disable clipping for the time being, issue needs to be resolved later"

This reverts commit 4f5f0fc36cc7f34fad05e45671dfa7b8dc32fd51.

* N-Gage: fix clipping issue by providing proper math functions

docs/README-ngage.md

@@ -0,0 +1,44 @@
+Nokia N-Gage
+============
+
+SDL2 port for Symbian S60v1/2 with a main focus on the Nokia N-Gage
+(Classic and QD) by [Michael Fitzmayer](https://github.com/mupfdev).
+
+Compiling
+---------
+
+SDL is part of the [N-Gage SDK.](https://github.com/ngagesdk) project.
+The library is included in the
+[toolchain](https://github.com/ngagesdk/ngage-toolchain) as a
+sub-module.
+
+A complete example project based on SDL2 can be found in the GitHub
+account of the SDK: [Example
+project](https://github.com/ngagesdk/wordle).
+
+Current level of implementation
+-------------------------------
+
+The video driver currently provides full screen video support with
+keyboard input.
+
+At the moment only the software renderer works.
+
+Audio is not yet implemented.
+
+Acknowledgements
+----------------
+
+Thanks to Hannu Viitala, Kimmo Kinnunen and Markus Mertama for the
+valuable insight into Symbian programming.  Without the SDL 1.2 port for
+CDoom, this adaptation would not have been possible.
+
+I would like to thank my friends
+[Razvan](https://twitter.com/bewarerazvan) and [Dan
+Whelan](https://danwhelan.ie/), for their continuous support.  Without
+you and the [N-Gage community](https://discord.gg/dbUzqJ26vs), I would
+have lost my patience long ago.
+
+Last but not least, I would like to say a special thank you to the
+[EKA2L1](https://12z1.com/) team.  Thank you for all your patience and
+support in troubleshooting.

docs/README.md

@@ -51,6 +51,7 @@ More documentation and FAQs are available online at [the wiki](http://wiki.libsd
 - [Windows](README-windows.md)
 - [WinRT](README-winrt.md)
 - [PSVita](README-vita.md)
+- [Nokia N-Gage](README-ngage.md)
 
 If you need help with the library, or just want to discuss SDL related
 issues, you can join the [SDL Discourse](https://discourse.libsdl.org/),