minigbm_helper: close the opened dir

BUG=b:205774533
TEST=no leak

Change-Id: I169dbf05f40f90266620a4b5cf0a8b7bb3c79d9e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/3282826
Tested-by: Yiwei Zhang <zzyiwei@chromium.org>
Reviewed-by: Chia-I Wu <olv@google.com>
Reviewed-by: Chad Versace <chadversary@chromium.org>
Commit-Queue: Yiwei Zhang <zzyiwei@chromium.org>
diff --git a/minigbm_helpers.c b/minigbm_helpers.c
index 137e5a1..cea0b48 100644
--- a/minigbm_helpers.c
+++ b/minigbm_helpers.c
@@ -273,6 +273,9 @@
 			break;
 		}
 	}
+
+	closedir(dir);
+
 	if (dfd >= 0)
 		return dfd;