Fixed most small problems reported by cppcheck for src/core PR #7307 (from @kevin2kevin2)

src/core/linux/SDL_evdev.c

@@ -782,7 +782,6 @@ static void SDL_EVDEV_sync_device(SDL_evdevlist_item *item)
 
 static int SDL_EVDEV_device_added(const char *dev_path, int udev_class)
 {
-    int ret;
     SDL_evdevlist_item *item;
     unsigned long relbit[NBITS(REL_MAX)] = { 0 };
 
@@ -819,6 +818,7 @@ static int SDL_EVDEV_device_added(const char *dev_path, int udev_class)
 
     /* For now, we just treat a touchpad like a touchscreen */
     if (udev_class & (SDL_UDEV_DEVICE_TOUCHSCREEN | SDL_UDEV_DEVICE_TOUCHPAD)) {
+        int ret;
         item->is_touchscreen = SDL_TRUE;
         ret = SDL_EVDEV_init_touchscreen(item, udev_class);
         if (ret < 0) {

src/core/linux/SDL_evdev_kbd.c

@@ -249,7 +249,7 @@ static void kbd_cleanup_signal_action(int signum, siginfo_t *info, void *ucontex
 
 static void kbd_unregister_emerg_cleanup()
 {
-    int tabidx, signum;
+    int tabidx;
 
     kbd_cleanup_state = NULL;
 
@@ -261,7 +261,7 @@ static void kbd_unregister_emerg_cleanup()
     for (tabidx = 0; tabidx < sizeof(fatal_signals) / sizeof(fatal_signals[0]); ++tabidx) {
         struct sigaction *old_action_p;
         struct sigaction cur_action;
-        signum = fatal_signals[tabidx];
+        int signum = fatal_signals[tabidx];
         old_action_p = &(old_sigaction[signum]);
 
         /* Examine current signal action */
@@ -290,7 +290,7 @@ static void kbd_cleanup_atexit(void)
 
 static void kbd_register_emerg_cleanup(SDL_EVDEV_keyboard_state *kbd)
 {
-    int tabidx, signum;
+    int tabidx;
 
     if (kbd_cleanup_state != NULL) {
         return;
@@ -314,7 +314,7 @@ static void kbd_register_emerg_cleanup(SDL_EVDEV_keyboard_state *kbd)
     for (tabidx = 0; tabidx < sizeof(fatal_signals) / sizeof(fatal_signals[0]); ++tabidx) {
         struct sigaction *old_action_p;
         struct sigaction new_action;
-        signum = fatal_signals[tabidx];
+        int signum = fatal_signals[tabidx];
         old_action_p = &(old_sigaction[signum]);
         if (sigaction(signum, NULL, old_action_p)) {
             continue;

src/core/linux/SDL_udev.c

@@ -152,8 +152,6 @@ int SDL_UDEV_Init(void)
 
 void SDL_UDEV_Quit(void)
 {
-    SDL_UDEV_CallbackList *item;
-
     if (_this == NULL) {
         return;
     }
@@ -173,7 +171,7 @@ void SDL_UDEV_Quit(void)
 
         /* Remove existing devices */
         while (_this->first != NULL) {
-            item = _this->first;
+            SDL_UDEV_CallbackList *item = _this->first;
             _this->first = _this->first->next;
             SDL_free(item);
         }