6604fb0 fileio: use take_fdopen_unlocked()

Authored and Committed by Yu Watanabe 2 years ago
    fileio: use take_fdopen_unlocked()
    
    This fixes maybe-uninitialized warning:
    ```
    ../src/basic/fileio.c: In function ‘chase_symlinks_and_fopen_unlocked’:
    ../src/basic/fileio.c:1026:19: warning: ‘f’ may be used uninitialized in this function [-Wmaybe-uninitialized]
     1026 |         *ret_file = f;
          |         ~~~~~~~~~~^~~
    
    ```
    
        
file modified
+2 -5