Get rid of some special cases for Cygwin in sys/types.h

Remove off_t typedef from cygwin/types.h thus relying on sys/types.h.
Introduce winsup/cygwin/machine/_types.h and move some types shared
with newlib into it.  Get rid of their definition in cygwin/types.h.
Add same handling for __key_t/key_t as for the other types.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/include/machine/_types.h

@@ -0,0 +1,26 @@
+/* Cygwin's machine/_types.h */
+
+#ifndef _MACHINE__TYPES_H
+#define _MACHINE__TYPES_H
+
+#include <machine/_default_types.h>
+
+#if defined (__INSIDE_CYGWIN__) || defined (_COMPILING_NEWLIB)
+typedef __int16_t  __dev16_t;
+typedef __uint16_t __uid16_t;
+typedef __uint16_t __gid16_t;
+#endif
+
+#define __dev_t_defined
+typedef __uint32_t __dev_t;
+
+#define __uid_t_defined
+typedef __uint32_t __uid_t;
+
+#define __gid_t_defined
+typedef __uint32_t __gid_t;
+
+#define __key_t_defined
+typedef long long __key_t;
+
+#endif /* _MACHINE__TYPES_H */