SDL: fix SDL_FindFreePlayerIndex so it can really return -1.

SDL Commits
1 
From 53bde3abee6bc64c3f5368c37e1b685ac18aafb3 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Wed, 8 Mar 2023 20:00:00 +0300
Subject: [PATCH] fix SDL_FindFreePlayerIndex so it can really return -1.

---
 src/joystick/SDL_joystick.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/joystick/SDL_joystick.c b/src/joystick/SDL_joystick.c
index d4096022aa70..49ff93432781 100644
--- a/src/joystick/SDL_joystick.c
+++ b/src/joystick/SDL_joystick.c
@@ -198,7 +198,7 @@ static SDL_bool SDL_GetDriverAndJoystickIndex(SDL_JoystickID instance_id, SDL_Jo
 
 static int SDL_FindFreePlayerIndex(void)
 {
-    int player_index = -1;
+    int player_index;
 
     SDL_AssertJoysticksLocked();
 
@@ -207,7 +207,7 @@ static int SDL_FindFreePlayerIndex(void)
             return player_index;
         }
     }
-    return player_index;
+    return -1;
 }
 
 static int SDL_GetPlayerIndexForJoystickID(SDL_JoystickID instance_id)