UT / clsync

Was "--check-exec-args"

Fixes: https://github.com/xaionaro/clsync/issues/121

Related: https://github.com/xaionaro/clsync/issues/124

Clsync uses effective pid of "nobody" by default. In turn there's
no permission to create new files in /var/run on some systems under
the "nobody". So this patch uses "root" to create and fchown() the
file.

    Debug3 (pid: 19860; thread: 0x7f606105db40): main(): Trying to drop effective gid to 65533
    Debug3 (pid: 19860; thread: 0x7f606105db40): main(): Trying to drop effective uid to 65534
    Debug1 (pid: 19860; thread: 0x7f606105db40): main(): / [/] (0xf7eed0) -> rsync://********@**********/******* [***] (0xf7ba30)
    Warning (pid: 19860; thread: 0x7f606105db40): main(): Directory "/dev/shm/clsync" doesn't exist. Creating it.
    Debug2 (pid: 19860; thread: 0x7f606105db40): main(): Trying to open the pidfile "/var/run/clsync-backup.pid"
    Error (pid: 19860; thread: 0x7f606105db40): main(): Cannot open file "/var/run/clsync***.pid" to write a pid there (13: Permission denied)
    Debug3 (pid: 19860; thread: 0x7f606105db40): main(): Current errno is 13.
    Error (pid: 19860; thread: 0x7f606105db40): main(): Cannot unlink pidfile "/var/run/clsync***.pid" (2: No such file or directory)

Conflicts:
	debian/clsync-doc.install
	debian/control
	debian/libclsync0.install
	man/man1/clsync.1

Closed the issue and updated the manpage

Function parse_customsignals() is adapted for atoi() and doesn't
work with xstrtol().

Temporary reversed xstrtol() to atoi() in this function

If errno is not reset before strtol call, it may trigger false str
to long conversation error, e.g. with absent /etc/{group,passwd}:

  # chroot /root/clsync /bin/clsync -M direct -W a -D b -r 10 -S /sbin/echo -t 1 -w 1 --secure-splitting
  Error: argument "10" can't be parsed as a number (2: No such file or directory)

Fixes: https://github.com/xaionaro/clsync/issues/115
Regressed by: 5e6cfe1d

Fixes: https://github.com/xaionaro/clsync/issues/117

For example "-Secho"

Fix of https://github.com/xaionaro/clsync/issues/102

https://github.com/xaionaro/clsync/issues/107

Reported by: anikeev@ut.mephi.ru

kernel patch and new args

Reported by: anikeev@ut.mephi.ru

(process:11827): GLib-CRITICAL **: g_key_file_get_value: assertion 'group_name != NULL' failed

https://lists.freebsd.org/pipermail/freebsd-arch/2008-February/007705.html