Fix typo for otherwise/0 in builtins.pl

Change-Id: If1135ef2faec7acd4429c9c9068dc001ac716149

src/builtin/builtins.pl

diff --git a/src/builtin/builtins.pl b/src/builtin/builtins.pl
index b0721c6..2d8e6cf 100644
--- a/src/builtin/builtins.pl
+++ b/src/builtin/builtins.pl
@@ -12,7 +12,7 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 % Control constructs
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-:- public true/0, therwise/0.
+:- public true/0, otherwise/0.
 :- public fail/0, false/0.
 :- public (!)/0.
 :- public (^)/2.