sdl12-compat: adjust the os/2 dll name in cmake the script.

SDL Commits
1 
From f83cde974bf9cf3ef9cc4583acdab645678899b5 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Thu, 2 Dec 2021 18:39:40 +0300
Subject: [PATCH] adjust the os/2 dll name in cmake the script.

---
 CMakeLists.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 61b5a39..2233a8b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -90,6 +90,12 @@ elseif(UNIX AND NOT ANDROID)
         VERSION "${SDL12_COMPAT_VERSION_STR}"
         SOVERSION "0"
         OUTPUT_NAME "SDL-1.2")
+elseif(OS2)
+    # OS/2 version was built as SDL12.dll
+    set_target_properties(SDL PROPERTIES
+        VERSION "${SDL12_COMPAT_VERSION_STR}"
+        SOVERSION "0"
+        OUTPUT_NAME "SDL12")
 else()
     set_target_properties(SDL PROPERTIES
         VERSION "${SDL12_COMPAT_VERSION_STR}"