chown: release resources before exiting

[anaelle.cazuc_stormshield.eu]

Summary

chown doesn't release the FTS handle when exiting, causing a memory leak
fts_close must be called before calling exit()

Test Plan

before:

$ valgrind --leak-check=full usr.sbin/chown/chown anaellec ~/a
==89707== Memcheck, a memory error detector
==89707== Copyright (C) 2002-2026, and GNU GPL'd, by Julian Seward et al.
==89707== Using Valgrind-3.27.1 and LibVEX; rerun with -h for copyright info
==89707== Command: usr.sbin/chown/chown anaellec /home/anaellec/a
==89707==
==89707==
==89707== HEAP SUMMARY:
==89707==     in use at exit: 8,250 bytes in 8 blocks
==89707==   total heap usage: 76 allocs, 68 frees, 54,127 bytes allocated
==89707==
==89707== 3,728 (2,448 direct, 1,280 indirect) bytes in 1 blocks are definitely lost in loss record 8 of 8
==89707==    at 0x48580F8: calloc (vg_replace_malloc.c:1620)
==89707==    by 0x4913797: fts_open (src/lib/libc/gen/fts.c:233)
==89707==    by 0x40023EA: main (usr.sbin/chown/chown.c:162)
==89707==
==89707== LEAK SUMMARY:
==89707==    definitely lost: 2,448 bytes in 1 blocks
==89707==    indirectly lost: 1,280 bytes in 1 blocks
==89707==      possibly lost: 0 bytes in 0 blocks
==89707==    still reachable: 4,522 bytes in 6 blocks
==89707==         suppressed: 0 bytes in 0 blocks
==89707== Reachable blocks (those to which a pointer was found) are not shown.
==89707== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==89707==
==89707== For lists of detected and suppressed errors, rerun with: -s
==89707== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

after:

$ valgrind --leak-check=full usr.sbin/chown/chown anaellec ~/a
==16283== Memcheck, a memory error detector
==16283== Copyright (C) 2002-2026, and GNU GPL'd, by Julian Seward et al.
==16283== Using Valgrind-3.27.1 and LibVEX; rerun with -h for copyright info
==16283== Command: usr.sbin/chown/chown anaellec /home/anaellec/a
==16283== 
==16283== 
==16283== HEAP SUMMARY:
==16283==     in use at exit: 4,522 bytes in 6 blocks
==16283==   total heap usage: 76 allocs, 70 frees, 54,127 bytes allocated
==16283== 
==16283== LEAK SUMMARY:
==16283==    definitely lost: 0 bytes in 0 blocks
==16283==    indirectly lost: 0 bytes in 0 blocks
==16283==      possibly lost: 0 bytes in 0 blocks
==16283==    still reachable: 4,522 bytes in 6 blocks
==16283==         suppressed: 0 bytes in 0 blocks
==16283== Reachable blocks (those to which a pointer was found) are not shown.
==16283== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==16283== 
==16283== For lists of detected and suppressed errors, rerun with: -s
==16283== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)