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/testiconv.c

@@ -0,0 +1,126 @@
+/*
+  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.
+*/
+
+/* quiet windows compiler warnings */
+#if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
+#define _CRT_SECURE_NO_WARNINGS
+#endif
+
+#include <stdio.h>
+
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+#include <SDL3/SDL_test.h>
+#include "testutils.h"
+
+static size_t
+widelen(char *data)
+{
+    size_t len = 0;
+    Uint32 *p = (Uint32 *)data;
+    while (*p++) {
+        ++len;
+    }
+    return len;
+}
+
+int main(int argc, char *argv[])
+{
+    const char *formats[] = {
+        "UTF8",
+        "UTF-8",
+        "UTF16BE",
+        "UTF-16BE",
+        "UTF16LE",
+        "UTF-16LE",
+        "UTF32BE",
+        "UTF-32BE",
+        "UTF32LE",
+        "UTF-32LE",
+        "UCS4",
+        "UCS-4",
+    };
+
+    char *fname = NULL;
+    char buffer[BUFSIZ];
+    char *ucs4;
+    char *test[2];
+    int i;
+    FILE *file;
+    int errors = 0;
+    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 */
+    for (i = 1; i < argc;) {
+        int consumed;
+
+        consumed = SDLTest_CommonArg(state, i);
+        if (!consumed) {
+            if (!fname) {
+                fname = argv[i];
+                consumed = 1;
+            }
+        }
+        if (consumed <= 0) {
+            static const char *options[] = { "[utf8.txt]", NULL };
+            SDLTest_CommonLogUsage(state, argv[0], options);
+            return 1;
+        }
+
+        i += consumed;
+    }
+
+    fname = GetResourceFilename(fname, "utf8.txt");
+    file = fopen(fname, "rb");
+    if (file == NULL) {
+        SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unable to open %s\n", fname);
+        return 1;
+    }
+    SDL_free(fname);
+
+    while (fgets(buffer, sizeof(buffer), file)) {
+        /* Convert to UCS-4 */
+        size_t len;
+        ucs4 =
+            SDL_iconv_string("UCS-4", "UTF-8", buffer,
+                             SDL_strlen(buffer) + 1);
+        len = (widelen(ucs4) + 1) * 4;
+        for (i = 0; i < SDL_arraysize(formats); ++i) {
+            test[0] = SDL_iconv_string(formats[i], "UCS-4", ucs4, len);
+            test[1] = SDL_iconv_string("UCS-4", formats[i], test[0], len);
+            if (!test[1] || SDL_memcmp(test[1], ucs4, len) != 0) {
+                SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "FAIL: %s\n", formats[i]);
+                ++errors;
+            }
+            SDL_free(test[0]);
+            SDL_free(test[1]);
+        }
+        test[0] = SDL_iconv_string("UTF-8", "UCS-4", ucs4, len);
+        SDL_free(ucs4);
+        (void)fputs(test[0], stdout);
+        SDL_free(test[0]);
+    }
+    (void)fclose(file);
+
+    SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION, "Total errors: %d\n", errors);
+    SDLTest_CommonDestroyState(state);
+    return errors ? errors + 1 : 0;
+}