Don't show gitlink directories when we want "other" files

When "show_other_directories" is set, that implies that we are looking
for untracked files, which obviously means that we should ignore
directories that are marked as gitlinks in the index.

This fixes "git status" in a superproject, that would otherwise always 
report that subprojects were "Untracked files:"

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 dir.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/dir.c b/dir.c
index 7b91501..6564a92 100644
--- a/dir.c
+++ b/dir.c

@@ -375,6 +375,8 @@ static enum directory_treatment treat_directory(struct dir_struct *dir,
 		return recurse_into_directory;
 
 	case index_gitdir:
+		if (dir->show_other_directories)
+			return ignore_directory;
 		return show_directory;
 
 	case index_nonexistent: