Implement basic clipboard support

zig/sdl/hello_sdl.zig

@@ -104,6 +104,27 @@ pub fn main() !void {
                                msg[max_chars] = 0;
                                pos = 0;
                            },
                            c.SDLK_c => {
                                const clipboard_text = try gpa.dupeZ(u8, result);
                                if (c.SDL_SetClipboardText(clipboard_text) != 0) {
                                    c.SDL_Log("Could not set clipboard text: %s", c.SDL_GetError());
                                }
                                gpa.free(clipboard_text);
                            },
                            c.SDLK_v => {
                                const clipboard_text = c.SDL_GetClipboardText();
                                if (std.mem.len(clipboard_text) == 0) {
                                    c.SDL_Log("Could not get clipboard: %s", c.SDL_GetError());
                                } else {
                                    const initial_pos = pos;
                                    while (pos < max_chars and pos - initial_pos < std.mem.len(clipboard_text)) : (pos += 1) {
                                        msg[pos] = clipboard_text[pos - initial_pos];
                                    }
                                    msg[pos] = ' ';
                                    msg[max_chars] = 0;
                                }
                                c.SDL_free(clipboard_text);
                            },
                            else => {},
                        }
                    } else {