SDL_native_midi: cmake: attempt to fix Windows builds.

SDL Commits
1 
From f704a684234df3f83c6567ae78ee6d6281354c32 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Thu, 26 Jun 2025 19:16:21 -0400
Subject: [PATCH] cmake: attempt to fix Windows builds.

Fixes #6.
---
 CMakeLists.txt | 1 +
 1 file changed, 1 insertion(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 473bdf9..a0651d3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,6 +21,7 @@ add_library(SDL_native_midi SHARED
 )
 target_include_directories(SDL_native_midi PRIVATE ${SDL3_INCLUDE_DIRS})
 target_link_libraries(SDL_native_midi PRIVATE ${SDL3_LIBRARIES})
+set_property(TARGET SDL_native_midi PROPERTY DEFINE_SYMBOL "DLL_EXPORT")
 if(WIN32)
     target_link_libraries(SDL_native_midi PRIVATE winmm)
 endif()