ctfconvert: Make the absence of debug info non-fatal

When compiled with gcc14, subr_ticks.o legitimately doesn't contain any
DWARF sections.  Just emit a warning in this case.  In general we still
want to run ctfconvert on asm files.

Reviewed by:	emaste, des
Fixes:		e959f2a7d8 ("ctf*: exit with error upon terminate()")
Differential Revision:	https://reviews.freebsd.org/D61231

cddl/contrib/opensolaris/tools/ctf/cvt/ctfconvert.c

@@ -230,8 +230,13 @@ main(int argc, char **argv)
 
 	filetd = tdata_new();
 
-	if (!file_read(filetd, infile, ignore_non_c))
-		terminate("%s doesn't have type data to convert\n", infile);
+	/*
+	 * asm files may legitimately not have debug info.
+	 */
+	if (!file_read(filetd, infile, ignore_non_c)) {
+		warning("%s doesn't have type data to convert\n", infile);
+		exit(0);
+	}
 
 	if (verbose)
 		iidesc_stats(filetd->td_iihash);