[newlib-cygwin] Cygwin: winchild: fix missing stdlib.h

[Jeremy Drake]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bf81e32f29e014312d87dd7eb1202c6e8e0fa959

commit bf81e32f29e014312d87dd7eb1202c6e8e0fa959
Author: Radek Bartoň <radek.barton@microsoft.com>
Date:   Tue Jul 1 17:49:55 2025 +0200

    Cygwin: winchild: fix missing stdlib.h
    
    The posix_spawn/winchild test was added recently by
    2af1914b6ad673a2041cf94cc8e78e1bdec57a27 commit. It fails to build for AArch64
    due to missing stdlib.h header where malloc and free functions are defined.
    This patch fixes the missing header.
    
    Signed-off-by: Radek Bartoň <radek.barton@microsoft.com>

Diff:
---
 winsup/testsuite/winsup.api/posix_spawn/winchild.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/winsup/testsuite/winsup.api/posix_spawn/winchild.c b/winsup/testsuite/winsup.api/posix_spawn/winchild.c
index 6fdfa002c..43fd35c58 100644
--- a/winsup/testsuite/winsup.api/posix_spawn/winchild.c
+++ b/winsup/testsuite/winsup.api/posix_spawn/winchild.c
@@ -3,7 +3,7 @@
 #include <winternl.h>
 #include <ctype.h>
 #include <stdio.h>
-
+#include <stdlib.h>
 
 int wmain (int argc, wchar_t **argv)
 {