[PATCH] prevent warnings while vompiling clib/syscalls

[Jaap de Wolff]

At this moment we get warnings while we compile the libc/syscalls folder.
This patch will prevent this

Jaap de Wolff
=======================PATCH===============================
diff --git a/newlib/libc/syscalls/sysisatty.c
b/newlib/libc/syscalls/sysisatty.c
index 697c54bc4..f4e8789ce 100644
--- a/newlib/libc/syscalls/sysisatty.c
+++ b/newlib/libc/syscalls/sysisatty.c
@@ -3,6 +3,11 @@
 #include <reent.h>
 #include <unistd.h>
 
+
+/* forward declaration */
+extern int _isatty_r(struct _reent *, int);
+extern int _isatty(int);
+
 int
 isatty (int fd)
 {