Strncat compile warning

[wcdanh2]

This code should be changed to compile without warnings.

| utils.c: In function 'get_all_hapd_conf_files':
| utils.c:1321:13: warning: 'strncat' specified bound depends on the length of the source argument [-Wstringop-overflow=]
| 1321 | strncat(conf_files, interfaces[i].hapd_conf_file, strlen(interfaces[i].hapd_conf_file));
| | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

https://github.com/Wi-FiQuickTrack/Wi-FiQuickTrack-ControlAppC/blame/a6bb580896cf8a985aba31cfc010a7fd11a9fc13/utils.c#L1321