Cygwin: always recognize AF_UNIX sockets as reparse points

If __WITH_AF_UNIX is defined when Cygwin is built, then a named
AF_UNIX socket is represented by a reparse point with a
Cygwin-specific tag and GUID.  Make such files recognizable as reparse
points (but not as sockets) even if __WITH_AF_UNIX is not defined.
That way utilities such as 'ls' and 'rm' still behave reasonably.

This requires two changes:

- Define the GUID __cygwin_socket_guid unconditionally.

- Make check_reparse_point_target return PATH_REP on a reparse point
  of this type if __WITH_AF_UNIX is not defined.

winsup/cygwin/fhandler_socket_unix.cc

@@ -8,9 +8,17 @@
    Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
    details. */
 
+#include "winsup.h"
+
+GUID __cygwin_socket_guid = {
+  .Data1 = 0xefc1714d,
+  .Data2 = 0x7b19,
+  .Data3 = 0x4407,
+  .Data4 = { 0xba, 0xb3, 0xc5, 0xb1, 0xf9, 0x2c, 0xb8, 0x8c }
+};
+
 #ifdef __WITH_AF_UNIX
 
-#include "winsup.h"
 #include <w32api/winioctl.h>
 #include <asm/byteorder.h>
 #include <unistd.h>
@@ -124,13 +132,6 @@ class af_unix_pkt_hdr_t
 	   (void *)(((PBYTE)(_p)) + AF_UNIX_PKT_OFFSETOF_DATA (_p)); \
 	})
 
-GUID __cygwin_socket_guid = {
-  .Data1 = 0xefc1714d,
-  .Data2 = 0x7b19,
-  .Data3 = 0x4407,
-  .Data4 = { 0xba, 0xb3, 0xc5, 0xb1, 0xf9, 0x2c, 0xb8, 0x8c }
-};
-
 /* Some error conditions on pipes have multiple status codes, unfortunately. */
 #define STATUS_PIPE_NO_INSTANCE_AVAILABLE(status)	\
 		({ NTSTATUS _s = (status); \

winsup/cygwin/path.cc

@@ -2476,8 +2476,7 @@ check_reparse_point_string (PUNICODE_STRING subst)
 /* Return values:
     <0: Negative errno.
      0: Not a reparse point recognized by us.
-    >0: PATH_SYMLINK | PATH_REP for symlink or directory mount point,
+    >0: Path flags for a recognized reparse point, always including PATH_REP.
-        PATH_SOCKET | PATH_REP for AF_UNIX socket.
 */
 int
 check_reparse_point_target (HANDLE h, bool remote, PREPARSE_DATA_BUFFER rp,
@@ -2618,15 +2617,18 @@ check_reparse_point_target (HANDLE h, bool remote, PREPARSE_DATA_BUFFER rp,
 	}
       return -EIO;
     }
-#ifdef __WITH_AF_UNIX
   else if (rp->ReparseTag == IO_REPARSE_TAG_CYGUNIX)
     {
       PREPARSE_GUID_DATA_BUFFER rgp = (PREPARSE_GUID_DATA_BUFFER) rp;
 
       if (memcmp (CYGWIN_SOCKET_GUID, &rgp->ReparseGuid, sizeof (GUID)) == 0)
+#ifdef __WITH_AF_UNIX
 	return PATH_SOCKET | PATH_REP;
+#else
+        /* Recognize this as a reparse point but not as a socket.  */
+        return PATH_REP;
+#endif
     }
-#endif /* __WITH_AF_UNIX */
   return 0;
 }