feat(gx): add incomplete 'CGxDeviceGLSDL' (#2)

* chore(build): add vendored SDL 3.0.0 library

* chore(build): add vendored glew-cmake-2.2.0 library

* feat(console): in the presence of -opengl launch flag, change GxApi to OpenGl

* feat(gx): add uncompleted CGxDeviceGLSDL targeting Windows and Linux

* chore(build): change SDL3 linkage from shared (bad) to to static (good)

vendor/sdl-3.0.0/test/testerror.c

@@ -0,0 +1,98 @@
+/*
+  Copyright (C) 1997-2023 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely.
+*/
+
+/* Simple test of the SDL threading code and error handling */
+
+#include <stdlib.h>
+
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+#include <SDL3/SDL_test.h>
+
+static int alive = 0;
+
+/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
+static void
+quit(int rc)
+{
+    SDL_Quit();
+    /* Let 'main()' return normally */
+    if (rc != 0) {
+        exit(rc);
+    }
+}
+
+static int SDLCALL
+ThreadFunc(void *data)
+{
+    /* Set the child thread error string */
+    SDL_SetError("Thread %s (%lu) had a problem: %s",
+                 (char *)data, SDL_ThreadID(), "nevermind");
+    while (alive) {
+        SDL_Log("Thread '%s' is alive!\n", (char *)data);
+        SDL_Delay(1 * 1000);
+    }
+    SDL_Log("Child thread error string: %s\n", SDL_GetError());
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    SDL_Thread *thread;
+    SDLTest_CommonState *state;
+
+    /* Initialize test framework */
+    state = SDLTest_CommonCreateState(argv, 0);
+    if (state == NULL) {
+        return 1;
+    }
+
+    /* Enable standard application logging */
+    SDL_LogSetPriority(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO);
+
+    /* Parse commandline */
+    if (!SDLTest_CommonDefaultArgs(state, argc, argv)) {
+        return 1;
+    }
+
+    /* Load the SDL library */
+    if (SDL_Init(0) < 0) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't initialize SDL: %s\n", SDL_GetError());
+        return 1;
+    }
+
+    /* Set the error value for the main thread */
+    SDL_SetError("No worries");
+
+    if (SDL_getenv("SDL_TESTS_QUICK") != NULL) {
+        SDL_Log("Not running slower tests");
+        SDL_Quit();
+        return 0;
+    }
+
+    alive = 1;
+    thread = SDL_CreateThread(ThreadFunc, NULL, "#1");
+    if (thread == NULL) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Couldn't create thread: %s\n", SDL_GetError());
+        quit(1);
+    }
+    SDL_Delay(5 * 1000);
+    SDL_Log("Waiting for thread #1\n");
+    alive = 0;
+    SDL_WaitThread(thread, NULL);
+
+    SDL_Log("Main thread error string: %s\n", SDL_GetError());
+
+    SDL_Quit();
+    SDLTest_CommonDestroyState(state);
+    return 0;
+}