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/src/thread/n3ds/SDL_syssem.c

@@ -0,0 +1,118 @@
+/*
+  Simple DirectMedia Layer
+  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, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#ifdef SDL_THREAD_N3DS
+
+/* An implementation of semaphores using libctru's LightSemaphore */
+
+#include <3ds.h>
+
+int WaitOnSemaphoreFor(SDL_Semaphore *sem, Sint64 timeout);
+
+struct SDL_Semaphore
+{
+    LightSemaphore semaphore;
+};
+
+SDL_Semaphore *SDL_CreateSemaphore(Uint32 initial_value)
+{
+    SDL_Semaphore *sem;
+
+    if (initial_value > SDL_MAX_SINT16) {
+        SDL_SetError("Initial semaphore value too high for this platform");
+        return NULL;
+    }
+
+    sem = (SDL_Semaphore *)SDL_malloc(sizeof(*sem));
+    if (sem == NULL) {
+        SDL_OutOfMemory();
+        return NULL;
+    }
+
+    LightSemaphore_Init(&sem->semaphore, initial_value, SDL_MAX_SINT16);
+
+    return sem;
+}
+
+/* WARNING:
+   You cannot call this function when another thread is using the semaphore.
+*/
+void SDL_DestroySemaphore(SDL_Semaphore *sem)
+{
+    SDL_free(sem);
+}
+
+int SDL_WaitSemaphoreTimeoutNS(SDL_Semaphore *sem, Sint64 timeoutNS)
+{
+    if (sem == NULL) {
+        return SDL_InvalidParamError("sem");
+    }
+
+    if (timeoutNS == -1) {  // -1 == wait indefinitely.
+        LightSemaphore_Acquire(&sem->semaphore, 1);
+        return 0;
+    }
+
+    if (LightSemaphore_TryAcquire(&sem->semaphore, 1) != 0) {
+        return WaitOnSemaphoreFor(sem, timeoutNS);
+    }
+
+    return 0;
+}
+
+int WaitOnSemaphoreFor(SDL_Semaphore *sem, Sint64 timeout)
+{
+    Uint64 stop_time = SDL_GetTicksNS() + timeout;
+    Uint64 current_time = SDL_GetTicksNS();
+    while (current_time < stop_time) {
+        if (LightSemaphore_TryAcquire(&sem->semaphore, 1) == 0) {
+            return 0;
+        }
+        /* 100 microseconds seems to be the sweet spot */
+        SDL_DelayNS(SDL_US_TO_NS(100));
+        current_time = SDL_GetTicksNS();
+    }
+
+    /* If we failed, yield to avoid starvation on busy waits */
+    SDL_DelayNS(1);
+    return SDL_MUTEX_TIMEDOUT;
+}
+
+Uint32 SDL_GetSemaphoreValue(SDL_Semaphore *sem)
+{
+    if (sem == NULL) {
+        SDL_InvalidParamError("sem");
+        return 0;
+    }
+    return sem->semaphore.current_count;
+}
+
+int SDL_PostSemaphore(SDL_Semaphore *sem)
+{
+    if (sem == NULL) {
+        return SDL_InvalidParamError("sem");
+    }
+    LightSemaphore_Release(&sem->semaphore, 1);
+    return 0;
+}
+
+#endif /* SDL_THREAD_N3DS */