trivial diff: sicstus.debug fix for --use-subdirs

[Peter David ROSS]

library/Mmakefile:
    Find the sp_builtin.ql file.


Index: Mmakefile
===================================================================
RCS file: /home/staff/zs/imp/mercury/library/Mmakefile,v
retrieving revision 1.31
diff -u -r1.31 Mmakefile
--- Mmakefile	1998/06/01 00:08:15	1.31
+++ Mmakefile	1998/06/01 06:50:06
@@ -38,7 +38,7 @@
 MSC	=	MERCURY_SICSTUS_COMPILER=./sicstus_compile $(SCRIPTS_DIR)/msc
 MSL	=	MERCURY_SP_LIB_DIR=. \
 		MERCURY_SICSTUS_PROLOG=./sicstus_saved_state \
-		MERCURY_SP_LIB_OBJS="`vpath_find sp_builtin.ql \
+		MERCURY_SP_LIB_OBJS="`vpath_find $(qls_subdir)sp_builtin.ql \
 				$(library.qls) $(NU_LIBRARY_QLS) \
 				$(qls_subdir)portray.ql`" \
 		MERCURY_SP_OVERRIDING_LIB_OBJS="$(NU_OVERRIDING_LIBRARY_QLS)" \