[newlib-cygwin] Fix ft32 libgloss for c99/gcc-14

[Jeff Law]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=886eadb78e94d77cf8f3f401158247fa695cf95b

commit 886eadb78e94d77cf8f3f401158247fa695cf95b
Author: Jeff Law <jeffreyalaw@gmail.com>
Date:   Fri Dec 22 20:48:21 2023 -0700

    Fix ft32 libgloss for c99/gcc-14
    
    Just one missing header for this libgloss port.

Diff:
---
 libgloss/ft32/sim-inbyte.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libgloss/ft32/sim-inbyte.c b/libgloss/ft32/sim-inbyte.c
index 9df0e1fe4..f56890dcc 100644
--- a/libgloss/ft32/sim-inbyte.c
+++ b/libgloss/ft32/sim-inbyte.c
@@ -13,6 +13,7 @@
  * the new terms are clearly indicated on the first page of each file where
  * they apply.
  */
+#include <unistd.h>
 
 int
 inbyte ()