Vendor raptor source files (was embedded gitlink)

Tree vendored at upstream 0019c5dd; origin + license recorded in
raptor/VENDOR.txt. Windows SDL dev packages excluded via .gitignore.

raptor/include/SDL2-devel-2.28.2-VC/SDL2-2.28.2/docs/README-psp.md

@@ -0,0 +1,36 @@
+PSP
+======
+SDL2 port for the Sony PSP contributed by:
+- Captian Lex
+- Francisco Javier Trujillo Mata
+- Wouter Wijsman
+
+
+Credit to
+   Marcus R.Brown,Jim Paris,Matthew H for the original SDL 1.2 for PSP
+   Geecko for his PSP GU lib "Glib2d"
+
+## Building
+To build SDL2 library for the PSP, make sure you have the latest PSPDev status and run:
+```bash
+cmake -S. -Bbuild -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE=$PSPDEV/psp/share/pspdev.cmake
+cmake --build build
+cmake --install build
+```
+
+
+## Getting PSP Dev
+[Installing PSP Dev](https://github.com/pspdev/pspdev)
+
+## Running on PPSSPP Emulator
+[PPSSPP](https://github.com/hrydgard/ppsspp)
+
+[Build Instructions](https://github.com/hrydgard/ppsspp/wiki/Build-instructions)
+
+
+## Compiling a HelloWorld
+[PSP Hello World](https://psp-dev.org/doku.php?id=tutorial:hello_world)
+
+## To Do
+- PSP Screen Keyboard
+- Dialogs