merge-ort: do leave trace2 region even if checkout fails

In 557ac0350d (merge-ort: begin performance work; instrument with
trace2_region_* calls, 2021-01-23), we added Trace2 instrumentation, but
in the error path that returns early, we forgot to tell Trace2 that
we're leaving the region. Let's fix that.

Pointed-out-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Reviewed-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

merge-ort.c

@@ -4226,6 +4226,7 @@ void merge_switch_to_result(struct merge_options *opt,
 			/* failure to function */
 			result->clean = -1;
 			merge_finalize(opt, result);
+			trace2_region_leave("merge", "checkout", opt->repo);
 			return;
 		}
 		trace2_region_leave("merge", "checkout", opt->repo);
@@ -4237,6 +4238,8 @@ void merge_switch_to_result(struct merge_options *opt,
 			opt->priv = NULL;
 			result->clean = -1;
 			merge_finalize(opt, result);
+			trace2_region_leave("merge", "record_conflicted",
+					    opt->repo);
 			return;
 		}
 		opt->priv = NULL;