Include the fast-import marks table in crash reports

If fast-import was not run with --export-marks but we are crashing
the frontend application developer may still benefit from having
that information available to them.  We now include the marks table
as part of the crash report if --export-marks was not supplied on
the command line.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fast-import.c

@@ -372,6 +372,8 @@ static void write_branch_report(FILE *rpt, struct branch *b)
 	fputc('\n', rpt);
 }
 
+static void dump_marks_helper(FILE *, uintmax_t, struct mark_set *);
+
 static void write_crash_report(const char *err)
 {
 	char *loc = git_path("fast_import_crash_%d", getpid());
@@ -443,6 +445,14 @@ static void write_crash_report(const char *err)
 		}
 	}
 
+	fputc('\n', rpt);
+	fputs("Marks\n", rpt);
+	fputs("-----\n", rpt);
+	if (mark_file)
+		fprintf(rpt, "  exported to %s\n", mark_file);
+	else
+		dump_marks_helper(rpt, 0, marks);
+
 	fputc('\n', rpt);
 	fputs("-------------------\n", rpt);
 	fputs("END OF CRASH REPORT\n", rpt);