Fixed double-backspace with hardware keyboard on iOS

(cherry picked from commit b7726026f8fd9d5bf3c39a8566162db23f755e7d)

src/video/uikit/SDL_uikitviewcontroller.m

@@ -581,7 +581,7 @@ static void SDLCALL SDL_HideHomeIndicatorHintChanged(void *userdata, const char
                 break;
             }
         }
-        if (matchLength < committedText.length) {
+        if (matchLength < committedText.length && !SDL_HasKeyboard()) {
             size_t deleteLength = SDL_utf8strlen([[committedText substringFromIndex:matchLength] UTF8String]);
             while (deleteLength > 0) {
                 // Send distinct down and up events for each backspace action