Fix a bug which prevented bootstrapping in MLDS grades.

Estimated hours taken: 0.75

Fix a bug which prevented bootstrapping in MLDS grades.

browser/program_representation.m:
	Export to C a function ML_goal_rep_type() which returns the
	type_info for a goal_rep.

trace/mercury_trace_internal.c:
	Use ML_goal_rep_type(), rather than hard-coding the mangled
	name for the type_ctor_info.  (The hard-coded mangled name
	was wrong for MLDS grades.)

browser/program_representation.m

@@ -33,7 +33,7 @@
 
 :- interface.
 
-:- import_module list.
+:- import_module list, std_util.
 
 	% A representation of the goal we execute.  These need to be
 	% generated statically and stored inside the executable.
@@ -126,5 +126,15 @@
 	;	erroneous_rep
 	;	failure_rep.
 
+	% Returns type_of(_ `with_type` goal_rep), for use in C code.
+:- func goal_rep_type = type_desc.
+
+%-----------------------------------------------------------------------------%
+
+:- implementation.
+
+:- pragma export(goal_rep_type = out, "ML_goal_rep_type").
+goal_rep_type = type_of(_ `with_type` goal_rep).
+
 %-----------------------------------------------------------------------------%
 %-----------------------------------------------------------------------------%

trace/mercury_trace_internal.c

@@ -28,6 +28,7 @@
 #include "mercury_trace_readline.h"
 
 #include "mdb.browse.h"
+#include "mdb.program_representation.h"
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -1741,8 +1742,6 @@ MR_trace_handle_cmd(char **words, int word_count, MR_Trace_Cmd_Info *cmd,
 			MR_trace_usage("help", "help");
 		}
 	} else if (streq(words[0], "proc_body")) {
-		extern const struct MR_TypeCtorInfo_Struct
-			mercury_data_mdb__program_representation__type_ctor_info_goal_rep_0;
 		const MR_Stack_Layout_Entry	*entry;
 
 		entry = event_info->MR_event_sll->MR_sll_entry;
@@ -1751,7 +1750,7 @@ MR_trace_handle_cmd(char **words, int word_count, MR_Trace_Cmd_Info *cmd,
 				"current procedure has no body info\n");
 		} else {
 			MR_trace_browse_internal(
-				(MR_Word) &mercury_data_mdb__program_representation__type_ctor_info_goal_rep_0,
+				ML_goal_rep_type(),
 				entry->MR_sle_proc_rep,
 				MR_BROWSE_CALLER_PRINT,
 				MR_BROWSE_DEFAULT_FORMAT);