Remove "get clipboard" call

Now that every device clipboard change is automatically synchronized to
the computer, the "get clipboard" request (bound to MOD+c) is useless.

app/scrcpy.1

@@ -292,10 +292,6 @@ Expand notification panel
 .B MOD+Shift+n
 Collapse notification panel
 
-.TP
-.B MOD+c
-Copy device clipboard to computer
-
 .TP
 .B MOD+v
 Paste computer clipboard to device

app/src/cli.c

@@ -260,9 +260,6 @@ scrcpy_print_usage(const char *arg0) {
         "    MOD+Shift+n\n"
         "        Collapse notification panel\n"
         "\n"
-        "    MOD+c\n"
-        "        Copy device clipboard to computer\n"
-        "\n"
         "    MOD+v\n"
         "        Paste computer clipboard to device\n"
         "\n"

app/src/input_manager.c

@@ -160,16 +160,6 @@ collapse_notification_panel(struct controller *controller) {
     }
 }
 
-static void
-request_device_clipboard(struct controller *controller) {
-    struct control_msg msg;
-    msg.type = CONTROL_MSG_TYPE_GET_CLIPBOARD;
-
-    if (!controller_push_msg(controller, &msg)) {
-        LOGW("Could not request device clipboard");
-    }
-}
-
 static void
 set_device_clipboard(struct controller *controller, bool paste) {
     char *text = SDL_GetClipboardText();
@@ -392,11 +382,6 @@ input_manager_process_key(struct input_manager *im,
                     rotate_client_right(im->screen);
                 }
                 return;
-            case SDLK_c:
-                if (control && !shift && !repeat && down) {
-                    request_device_clipboard(controller);
-                }
-                return;
             case SDLK_v:
                 if (control && !repeat && down) {
                     if (shift) {