memory leak fix

[LeeYoung624]

Pointer path points to a memory which is malloced in the while loop, but it's not freed before continue

[felixhandte]

Hey, great catch! This is obviously a leak by inspection, and I can in fact trigger it in valgrind, by compressing a directory that has a symlink in it:

felixh@vali:~/prog/zstd (dev)$ ls -lh tmp/
total 4.0K
-rw-rw-r-- 1 felixh felixh 3 Jul 25 11:46 a
lrwxrwxrwx 1 felixh felixh 1 Jul 25 11:46 a.sl -> a
felixh@vali:~/prog/zstd (dev)$ valgrind --leak-check=full ./zstd -r tmp
==20602== Memcheck, a memory error detector
==20602== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==20602== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==20602== Command: ./zstd -r tmp
==20602== 
Warning : tmp/a.sl is a symbolic link, ignoring
tmp/a                :533.33%   (     3 =>     16 bytes, tmp/a.zst)            
==20602== 
==20602== HEAP SUMMARY:
==20602==     in use at exit: 48 bytes in 2 blocks
==20602==   total heap usage: 16 allocs, 14 frees, 330,405 bytes allocated
==20602== 
==20602== 9 bytes in 1 blocks are definitely lost in loss record 1 of 2
==20602==    at 0x4C2FB0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==20602==    by 0x1D7AD8: UTIL_prepareFileList (in /home/felixh/prog/zstd/zstd)
==20602==    by 0x1D7F28: UTIL_createFileList (in /home/felixh/prog/zstd/zstd)
==20602==    by 0x10BFB9: main (in /home/felixh/prog/zstd/zstd)
==20602== 
==20602== LEAK SUMMARY:
==20602==    definitely lost: 9 bytes in 1 blocks
==20602==    indirectly lost: 0 bytes in 0 blocks
==20602==      possibly lost: 0 bytes in 0 blocks
==20602==    still reachable: 39 bytes in 1 blocks
==20602==         suppressed: 0 bytes in 0 blocks
==20602== Reachable blocks (those to which a pointer was found) are not shown.
==20602== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==20602== 
==20602== For counts of detected and suppressed errors, rerun with: -v
==20602== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
felixh@vali:~/prog/zstd (dev)$ 

This fix is pretty obviously right, I'm going to merge it into the release in progress now. Thanks for your contribution!