A lock another holder has is 'again', not an input-output failure

⚠️⚠️ THE TRANSLATION TABLE HAD NO ENTRY FOR A LOCK CONFLICT, because nothing in
this implementation took a lock until openkal 0.10.

`kal_fs_lock' without KAL_LOCK_WAIT reports `kal_err_again' where the range is
held --- that is the answer a caller POLLS UPON, and openkal says so. Without the
entry, `ERROR_LOCK_VIOLATION' fell to the default arm and became `kal_err_io':
a failure of the DEVICE rather than a conflict with another holder. A caller
reading that stops; a caller reading `again' retries.

⭐ IT IS DISTINCT FROM `ERROR_SHARING_VIOLATION', WHICH STAYS `permission'.
That one is a conflict over how a file was OPENED and is not resolved by asking
again. Two errors that look adjacent and mean opposite things for a caller.

Found by the specification's own conformance suite, on the observation added with
the operation --- which is the argument for adding the observation with the
operation.

Author: Sunrisepeak

src/win.cpp

@@ -55,6 +55,20 @@ int translate_win32(unsigned long e) {
         case ERROR_ALREADY_EXISTS:          return kal_err_exists;
         case ERROR_DIR_NOT_EMPTY:           return kal_err_not_empty;
         case ERROR_DIRECTORY:               return kal_err_not_directory;
+        // ⚠️⚠️ A LOCK THAT ANOTHER HOLDER HAS IS `AGAIN' AND NOT AN
+        // INPUT-OUTPUT FAILURE, and this line is missing from every earlier
+        // release because nothing here took a lock until openkal 0.10.
+        //
+        // `kal_fs_lock' without KAL_LOCK_WAIT reports kal_err_again where the
+        // range is held, which is the answer a caller POLLS UPON. Falling to
+        // the arm below would have reported kal_err_io --- a failure of the
+        // device rather than a conflict with another holder --- and a caller
+        // reading that would stop rather than retry.
+        //
+        // ⭐ It is distinct from ERROR_SHARING_VIOLATION above, which stays
+        // `permission': that one is a conflict over how a file was OPENED and
+        // is not resolved by asking again.
+        case ERROR_LOCK_VIOLATION:          return kal_err_again;
         case ERROR_IO_PENDING:              return kal_err_again;
         default:                            return kal_err_io;
     }

src/win32.h

@@ -216,6 +216,7 @@ enum : DWORD {
     ERROR_OUTOFMEMORY           = 14,
     ERROR_WRITE_PROTECT         = 19,
     ERROR_SHARING_VIOLATION     = 32,
+    ERROR_LOCK_VIOLATION        = 33,
     ERROR_HANDLE_EOF            = 38,
     ERROR_HANDLE_DISK_FULL      = 39,
     ERROR_NOT_SUPPORTED         = 50,