SDL: vfork() isn't functional on DOS

SDL Commits
1 
From 91173aba25266194408c9d401e511395a732c2b5 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 2 Jun 2026 12:23:14 -0700
Subject: [PATCH] vfork() isn't functional on DOS

---
 cmake/PreseedDOSCache.cmake | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cmake/PreseedDOSCache.cmake b/cmake/PreseedDOSCache.cmake
index 1b2a70aab41bd..2e523c863132e 100644
--- a/cmake/PreseedDOSCache.cmake
+++ b/cmake/PreseedDOSCache.cmake
@@ -141,7 +141,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL "DOS")
       set(LIBC_HAS_TRUNC                                 "1"   CACHE INTERNAL "Have symbol trunc")
       set(LIBC_HAS_TRUNCF                                "1"   CACHE INTERNAL "Have symbol truncf")
       set(LIBC_HAS_UNSETENV                              "1"   CACHE INTERNAL "Have symbol unsetenv")
-      set(LIBC_HAS_VFORK                                 "1"   CACHE INTERNAL "Have symbol vfork")
+      set(LIBC_HAS_VFORK                                 ""    CACHE INTERNAL "Have symbol vfork")
       set(LIBC_HAS_VSNPRINTF                             "1"   CACHE INTERNAL "Have symbol vsnprintf")
       set(LIBC_HAS_VSSCANF                               "1"   CACHE INTERNAL "Have symbol vsscanf")
       set(LIBC_HAS_WCHAR_H                               "1"   CACHE INTERNAL "Have include wchar.h")