Add FUSE_FILL_DIR_DEFAULTS enum (#903)

In order to use the fuse_fill_dir_t function in a C++ program, add the enum item:
FUSE_FILL_DIR_DEFAULTS

Without this change g++ compilation failed with
example/hello.c:94:35: error: invalid conversion from ‘int’ to ‘fuse_fill_dir_flags’ [-fpermissive]
   94 |         filler(buf, ".", NULL, 0, 0);
      |                                   ^
      |                                   |
      |                                   int

1 files changed, 1 insertions, 1 deletions

diff --git a/example/poll.c b/example/poll.c
index fd53ec0..ffcb4f1 100644
--- a/example/poll.c
+++ b/example/poll.c
@@ -114,7 +114,7 @@ static int fsel_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
 
 	for (i = 0; i < FSEL_FILES; i++) {
 		name[0] = fsel_hex_map[i];
-		filler(buf, name, NULL, 0, 0);
+		filler(buf, name, NULL, 0, FUSE_FILL_DIR_DEFAULTS);
 	}
 
 	return 0;