Fixed compilation with C89 (thanks @d-s-a!)

Closes https://github.com/libsdl-org/SDL/pull/9564

(cherry picked from commit 4e29be814e2a67992e7487b2b1814e37ff4c6980)

src/video/kmsdrm/SDL_kmsdrmvideo.c

@@ -77,6 +77,7 @@ static int get_driindex(void)
     int devindex = -1;
     DIR *folder;
     const char *hint;
+    struct dirent *res;
 
     hint = SDL_GetHint(SDL_HINT_KMSDRM_DEVICE_INDEX);
     if (hint && *hint) {
@@ -96,7 +97,7 @@ static int get_driindex(void)
 
     SDL_strlcpy(device + kmsdrm_dri_pathsize, kmsdrm_dri_devname,
                 sizeof(device) - kmsdrm_dri_devnamesize);
-    for (struct dirent *res; (res = readdir(folder));) {
+    while((res = readdir(folder)) != NULL) {
         if (SDL_memcmp(res->d_name, kmsdrm_dri_devname,
                        kmsdrm_dri_devnamesize) == 0) {
             SDL_strlcpy(device + kmsdrm_dri_pathsize + kmsdrm_dri_devnamesize,

src/video/wayland/SDL_waylandevents.c

@@ -1166,7 +1166,8 @@ static void keyboard_handle_enter(void *data, struct wl_keyboard *keyboard,
         const SDL_Scancode scancode = Wayland_get_scancode_from_key(input, *key + 8);
 
         if (scancode != SDL_SCANCODE_UNKNOWN) {
-            for (uint32_t i = 0; i < SDL_arraysize(mod_scancodes); ++i) {
+            uint32_t i;
+            for (i = 0; i < SDL_arraysize(mod_scancodes); ++i) {
                 if (mod_scancodes[i] == scancode) {
                     SDL_SendKeyboardKey(SDL_PRESSED, scancode);
                     break;
@@ -1814,7 +1815,8 @@ static void data_device_handle_drop(void *data, struct wl_data_device *wl_data_d
                     char **paths = SDL_DBus_DocumentsPortalRetrieveFiles(buffer, &path_count);
                     /* If dropped files contain a directory the list is empty */
                     if (paths && path_count > 0) {
-                        for (int i = 0; i < path_count; i++) {
+                        int i;
+                        for (i = 0; i < path_count; i++) {
                             SDL_SendDropFile(data_device->dnd_window, paths[i]);
                         }
                         dbus->free_string_array(paths);