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/video/cocoa/SDL_cocoaopengl.h

@@ -0,0 +1,89 @@
+/*
+  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"
+
+#ifndef SDL_cocoaopengl_h_
+#define SDL_cocoaopengl_h_
+
+#ifdef SDL_VIDEO_OPENGL_CGL
+
+#import <Cocoa/Cocoa.h>
+#import <QuartzCore/CVDisplayLink.h>
+
+/* We still support OpenGL as long as Apple offers it, deprecated or not, so disable deprecation warnings about it. */
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+#endif
+
+struct SDL_GLDriverData
+{
+    int initialized;
+};
+
+@interface SDLOpenGLContext : NSOpenGLContext
+{
+    SDL_AtomicInt dirty;
+    SDL_Window *window;
+    CVDisplayLinkRef displayLink;
+  @public
+    SDL_Mutex *swapIntervalMutex;
+  @public
+    SDL_Condition *swapIntervalCond;
+  @public
+    SDL_AtomicInt swapIntervalSetting;
+  @public
+    SDL_AtomicInt swapIntervalsPassed;
+}
+
+- (id)initWithFormat:(NSOpenGLPixelFormat *)format
+        shareContext:(NSOpenGLContext *)share;
+- (void)scheduleUpdate;
+- (void)updateIfNeeded;
+- (void)movedToNewScreen;
+- (void)setWindow:(SDL_Window *)window;
+- (SDL_Window *)window;
+- (void)explicitUpdate;
+- (void)cleanup;
+
+@property(retain, nonatomic) NSOpenGLPixelFormat *openglPixelFormat; // macOS 10.10 has -[NSOpenGLContext pixelFormat] but this handles older OS releases.
+
+@end
+
+/* OpenGL functions */
+extern int Cocoa_GL_LoadLibrary(SDL_VideoDevice *_this, const char *path);
+extern SDL_FunctionPointer Cocoa_GL_GetProcAddress(SDL_VideoDevice *_this, const char *proc);
+extern void Cocoa_GL_UnloadLibrary(SDL_VideoDevice *_this);
+extern SDL_GLContext Cocoa_GL_CreateContext(SDL_VideoDevice *_this, SDL_Window *window);
+extern int Cocoa_GL_MakeCurrent(SDL_VideoDevice *_this, SDL_Window *window,
+                                SDL_GLContext context);
+extern int Cocoa_GL_SetSwapInterval(SDL_VideoDevice *_this, int interval);
+extern int Cocoa_GL_GetSwapInterval(SDL_VideoDevice *_this, int *interval);
+extern int Cocoa_GL_SwapWindow(SDL_VideoDevice *_this, SDL_Window *window);
+extern int Cocoa_GL_DeleteContext(SDL_VideoDevice *_this, SDL_GLContext context);
+
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+
+#endif /* SDL_VIDEO_OPENGL_CGL */
+
+#endif /* SDL_cocoaopengl_h_ */