Improve os.listdir

os.pxd

@@ -6,6 +6,8 @@ from libc.errno cimport errno
 from libc.stdio cimport FILE, fopen, fclose, fread, fwrite, ferror
 from libc.stdio cimport stdin, stdout, stderr
 
+from libc.string cimport strcmp
+
 from posix cimport unistd
 
 from ._os cimport DIR, struct_dirent, opendir, readdir, closedir
@@ -50,6 +52,8 @@ cdef inline List[Str] listdir(Str path) nogil:
         entry = readdir(d)
         if entry is NULL:
             break
+        if strcmp(entry.d_name, b'.') == 0 or strcmp(entry.d_name, b'..') == 0:
+            continue
         entries.append(Str(entry.d_name))
     read_error = errno
     closedir(d)