sdl2-compat: Makefile.linux: add -DSDL2COMPAT_HAVE_X11 to CFLAGS

From e60cfb20e03f5d9c3a67a5697a9735715efcf64f Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Sun, 12 Oct 2025 22:11:50 +0300
Subject: [PATCH] Makefile.linux: add -DSDL2COMPAT_HAVE_X11 to CFLAGS

---
 src/Makefile.linux | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/Makefile.linux b/src/Makefile.linux
index 3cff057..a928288 100644
--- a/src/Makefile.linux
+++ b/src/Makefile.linux
@@ -6,11 +6,10 @@ INCLUDES = -Iinclude
 CC = gcc
 LD = $(CC)
 
-CPPFLAGS = -DNDEBUG -D_THREAD_SAFE -D_REENTRANT -DSDL_INCLUDE_STDBOOL_H
+CPPFLAGS = -DNDEBUG -D_THREAD_SAFE -D_REENTRANT -DSDL_INCLUDE_STDBOOL_H -DSDL2COMPAT_HAVE_X11
 
 CFLAGS  = -fPIC -fvisibility=hidden -O3 -Wall
 LDFLAGS = -shared -Wl,-soname,libSDL2-2.0.so.0
-# make sure this is supported:
 LDFLAGS+= -Wl,--no-undefined
 LDLIBS  = -ldl