SDL: Fixed interpreting SDL_KMSDRM_DEVICE_INDEX="" as index 0

SDL Commits
1 
From 613ce7850e579b628361a2692e21e9aa33889b22 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 26 Jul 2022 13:34:27 -0700
Subject: [PATCH] Fixed interpreting SDL_KMSDRM_DEVICE_INDEX="" as index 0

---
 src/video/kmsdrm/SDL_kmsdrmvideo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/video/kmsdrm/SDL_kmsdrmvideo.c b/src/video/kmsdrm/SDL_kmsdrmvideo.c
index b66e71538c3..92ecc2d909f 100644
--- a/src/video/kmsdrm/SDL_kmsdrmvideo.c
+++ b/src/video/kmsdrm/SDL_kmsdrmvideo.c
@@ -80,7 +80,7 @@ get_driindex(void)
     const char *hint;
 
     hint = SDL_GetHint(SDL_HINT_KMSDRM_DEVICE_INDEX);
-    if (hint) {
+    if (hint && *hint) {
         const int idx = SDL_atoi(hint);
         if (idx >= 0) {
             return idx;  /* we'll take the user's request here. */