sssd: fix faulty program detection inside is_running_sssd

[jengelh]

The is_running_sssd function erroneously returns false even though the program binary is called sssd. This is because it looks at the wrong portion of the filename.

Observed:

…
(gdb) r
…
is_running_sssd () at src/util/sss_ini.c:156
156         const char *s = NULL;
(gdb) n
158         ret = readlink("/proc/self/exe", exe, sizeof(exe) - 1);
159         if ((ret > 0) && (ret < 1024)) {
160             exe[ret] = 0;
161             s = strstr(exe, debug_prg_name);
(gdb) p exe
$6 = "/home/ej/repos/sssd/.libs/sssd", '\000' <repeats 993 times>
(gdb) p debug_prg_name
$7 = 0x7ffff77fc110 "sssd"
(gdb) p s
$8 = 0x7ffff7fa72cf <exe+15> "sssd/.libs/sssd"

Expected:

(gdb) p s
$8 = 0x7ffff7fa72da <exe+26> "sssd"

Fixes: 2.9.0-453-g9fbaf6d74

[alexey-tikhonov]

Thank you, ACK.

[alexey-tikhonov]

Function is_running_sssd() might become obsolete, 'll see.

[alexey-tikhonov]

Superseded by #7667