[newlib-cygwin] Add missing includes.

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=e8b23909e4f458b923595872719523b2293bd74e

commit e8b23909e4f458b923595872719523b2293bd74e
Author: Andrew Stubbs <ams@codesourcery.com>
Date:   Mon Mar 25 15:33:53 2019 +0000

    Add missing includes.
    
    These missing includes were causing build warnings, but also a real bug in
    which the "size" parameter to "write" was being passed in 32-bit, whereas it
    ought to be 64-bit.  This led to intermittent bad behaviour.

Diff:
---
 newlib/libc/machine/amdgcn/abort.c    | 2 +-
 newlib/libc/machine/amdgcn/getreent.c | 1 +
 newlib/libc/sys/amdgcn/fstat.c        | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/newlib/libc/machine/amdgcn/abort.c b/newlib/libc/machine/amdgcn/abort.c
index ccbca72..ca9a0a3 100644
--- a/newlib/libc/machine/amdgcn/abort.c
+++ b/newlib/libc/machine/amdgcn/abort.c
@@ -13,7 +13,7 @@
  * they apply.
  */
 
-#include <stdlib.h>
+#include <unistd.h>
 #include <signal.h>
 #include "exit-value.h"
 
diff --git a/newlib/libc/machine/amdgcn/getreent.c b/newlib/libc/machine/amdgcn/getreent.c
index acf10a9..5a28aa4 100644
--- a/newlib/libc/machine/amdgcn/getreent.c
+++ b/newlib/libc/machine/amdgcn/getreent.c
@@ -3,6 +3,7 @@
 #include <reent.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 /* Copied from the HSA documentation.  */
 typedef struct hsa_signal_s {
diff --git a/newlib/libc/sys/amdgcn/fstat.c b/newlib/libc/sys/amdgcn/fstat.c
index b787158..2526967 100644
--- a/newlib/libc/sys/amdgcn/fstat.c
+++ b/newlib/libc/sys/amdgcn/fstat.c
@@ -13,6 +13,8 @@
  * they apply.
  */
 
+#include <sys/types.h>
+#include <sys/stat.h>
 #include <unistd.h>
 #include <errno.h>