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>

newlib/libc/include/sys/_types.h

@@ -45,6 +45,10 @@ typedef _off_t __off_t;
 
 typedef _off64_t __loff_t;
 
+#ifndef __key_t_defined
+typedef long __key_t;
+#endif
+
 /*
  * We need fpos_t for the following, but it doesn't have a leading "_",
  * so we use _fpos_t instead.

newlib/libc/include/sys/types.h

@@ -167,7 +167,6 @@ typedef int32_t register_t;
  * how the file was compiled (e.g. -mint16 vs -mint32, etc.).
  */
 
-#ifndef __CYGWIN__	/* which defines these types in it's own types.h. */
 #ifndef _OFF_T_DECLARED
 typedef	__off_t		off_t;		/* file offset */
 #define	_OFF_T_DECLARED
@@ -184,7 +183,6 @@ typedef	__uid_t		uid_t;		/* user id */
 typedef	__gid_t		gid_t;		/* group id */
 #define	_GID_T_DECLARED
 #endif
-#endif /* !__CYGWIN__ */
 
 #ifndef _PID_T_DECLARED
 typedef	__pid_t		pid_t;		/* process id */
@@ -195,8 +193,9 @@ typedef	__pid_t		pid_t;		/* process id */
 typedef _mode_t mode_t;
 #endif
 
-#ifndef __CYGWIN__
-typedef	long key_t;
+#ifndef _KEY_T_DECLARED
+typedef	__key_t		key_t;		/* IPC key */
+#define	_KEY_T_DECLARED
 #endif
 
 #ifndef _SSIZE_T_DECLARED