sdl12-compat: Restrict X11_KeyToUnicode to unix builds.

SDL Commits
1 
From d05899f95c5d7e7e2d8eee40ddf3815e53a3bddf Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Thu, 16 Dec 2021 14:00:32 +0300
Subject: [PATCH] Restrict X11_KeyToUnicode to unix builds.

Reference issue #153.
---
 src/SDL12_compat.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 6647bc7..ef62faa 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -8102,13 +8102,14 @@ SDL_GL_EnableContext_Thread(void)
    As this isn't X11-specific, we supply it globally, so x11 binaries can transition
    to Wayland, and if there's some wildly-misbuilt win32 software, they can call it
    too. :) */
-
+#if !(defined(_WIN32) || defined(__OS2__)) /* #if defined(__unix__) || defined(__APPLE__) ?? */
 DECLSPEC Uint16 SDLCALL
 X11_KeyToUnicode(SDL12Key key, SDL12Mod mod)
 {
     if (((int) key) >= 127) {
         return 0;
-    } else if ((key >= SDLK12_a) && (key <= SDLK12_z)) {
+    }
+    if ((key >= SDLK12_a) && (key <= SDLK12_z)) {
         const int shifted = ((mod & (KMOD12_LSHIFT|KMOD12_RSHIFT)) != 0) ? 1 : 0;
         int capital = ((mod & KMOD12_CAPS) != 0) ? 1 : 0;
         if (shifted) {
@@ -8119,6 +8120,7 @@ X11_KeyToUnicode(SDL12Key key, SDL12Mod mod)
 
     return (Uint16) key;
 }
+#endif
 
 #ifdef __cplusplus
 }