BUG/MINOR: haproxy: Free uri_auth->scope during deinit

BUG/MINOR: haproxy: Free uri_auth->scope during deinit

Given the following example configuration:

    listen http
    	bind *:80
    	mode http
    	stats scope .

Running a configuration check with valgrind reports:

    ==16341== 26 (24 direct, 2 indirect) bytes in 1 blocks are definitely lost in loss record 3 of 13
    ==16341==    at 0x4C2FB55: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
    ==16341==    by 0x571C2E: stats_add_scope (uri_auth.c:296)
    ==16341==    by 0x46CE29: cfg_parse_listen (cfgparse-listen.c:1901)
    ==16341==    by 0x45A112: readcfgfile (cfgparse.c:2078)
    ==16341==    by 0x50A0F5: init (haproxy.c:1828)
    ==16341==    by 0x418248: main (haproxy.c:3012)

After this patch is applied the leak is gone as expected.

This is a very minor leak that can only be observed if deinit() is called,
shortly before the OS will free all memory of the process anyway. No
backport needed.