make get_unused_fd_flags() a function

... and get_unused_fd() a macro around it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/file.c b/fs/file.c
index ba3f605..5b46e99 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -477,8 +477,8 @@
 	return error;
 }
 
-int get_unused_fd(void)
+int get_unused_fd_flags(unsigned flags)
 {
-	return alloc_fd(0, 0);
+	return alloc_fd(0, flags);
 }
-EXPORT_SYMBOL(get_unused_fd);
+EXPORT_SYMBOL(get_unused_fd_flags);