SDL_mixer: Fixed setting the distdir since this package doesn't use automake

SDL Commits
#1 
From d881b5051b6e6f494ab75247b27627847bee898a Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Thu, 16 Jun 2022 18:34:54 -0700
Subject: [PATCH] Fixed setting the distdir since this package doesn't use
 automake

---
 Makefile.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile.in b/Makefile.in
index deffdd53..618a82f5 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -13,7 +13,7 @@ datadir	= @datadir@
 mandir	= @mandir@
 auxdir	= @ac_aux_dir@
 distpath = $(srcdir)/..
-distdir = SDL2_mixer-@VERSION@
+distdir = @PACKAGE_NAME@-@PACKAGE_VERSION@
 distfile = $(distdir).tar.gz
 
 @SET_MAKE@