[newlib-cygwin] Fix another missing header file for mcore libgloss

[Jeff Law]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=7ef32a98cdf74157ae734a7a833af5171585db0c

commit 7ef32a98cdf74157ae734a7a833af5171585db0c
Author: Jeff Law <jeffreyalaw@gmail.com>
Date:   Fri Dec 29 21:23:26 2023 -0700

    Fix another missing header file for mcore libgloss
    
    I guess I must have missed this when working through the trivial port specific
    changes.
    
    This adds an include of stdlib.h to get a prototype for exit().
    
    Pushed to the trunk.

Diff:
---
 libgloss/mcore/sbrk.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libgloss/mcore/sbrk.c b/libgloss/mcore/sbrk.c
index 1eb8047fc..c6860194c 100644
--- a/libgloss/mcore/sbrk.c
+++ b/libgloss/mcore/sbrk.c
@@ -14,6 +14,7 @@
  */
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <stdlib.h>
 #include "glue.h"
 
 extern int _write (int, char *, int);