generalize resolve_directory into resolve_path, fix mkdir, cd, update rm, create, add rmdir

inc/fs.h

@@ -1,5 +1,7 @@
 #include "config.h"
 
+#define FOLLOW_LAST_SYMLINK 0x1
+
 enum fs_filetype {
 	REGULAR,
 	DIRECTORY
@@ -69,6 +71,7 @@ int fs_read(void *d);
 int fs_write(void *d);
 int fs_close(void *d);
 int fs_mkdir(void *d);
+int fs_rmdir(void *d);
 int fs_cd(void *d);
 int fs_truncate(void *d);
 int fs_allow_write(void *d);