trivial diff: fix incorrect prototype

[Simon Taylor]

Estimated hours taken: 0.01

mercury_init.h:
	ML_DI_get_var_number() returns Integer not int. This caused
	compilation of the library to fail on murlibobo.


Index: mercury_init.h
===================================================================
RCS file: /home/staff/zs/imp/mercury/runtime/mercury_init.h,v
retrieving revision 1.5
diff -u -t -u -r1.5 mercury_init.h
--- mercury_init.h	1998/07/31 15:14:12	1.5
+++ mercury_init.h	1998/08/02 04:08:20
@@ -112,7 +112,7 @@
 bool    ML_DI_found_match(Integer, Integer, Integer, Word, String, String,
                 Integer, Integer, Integer, Word, String, Word);
                 /* normally ML_DI_found_match (found_match/12) */
-int     ML_DI_get_var_number(Word);
+Integer ML_DI_get_var_number(Word);
 void    ML_DI_read_request_from_socket(Word, Word *, Integer *);
 
 /* in library/std_util.m  */