[ntp]: build ntp with various fixes

[lguohan]

- Why I did it

• NTP Bug 1970 (UNLINK_EXPR_SLIST empty list) Fix
• ENOBUFS log message level set to WARN
• Fix audit message seen on console apparmor

Signed-off-by: Guohan Lu [email protected]

- How I did it

- How to verify it
extracted from #6033

- Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006

- Description for the changelog

- A picture of a cute animal (not mandatory but encouraged)

[lguohan]

@PrabhuSreenivasan to take a look.

[lguohan]

build error:

09:06:15  debconf: delaying package configuration, since apt-utils is not installed
09:06:15  Fetched 88.7 kB in 0s (307 kB/s)
09:06:15  E: Can not write log (Is /dev/pts mounted?) - posix_openpt (2: No such file or directory)
09:06:15  Selecting previously unselected package netbase.
09:06:15  (Reading database ... 28049 files and directories currently installed.)
09:06:15  Preparing to unpack .../archives/netbase_5.6_all.deb ...
09:06:15  Unpacking netbase (5.6) ...
09:06:15  Selecting previously unselected package libopts25:amd64.
09:06:15  Preparing to unpack .../libopts25_1%3a5.18.12-4_amd64.deb ...
09:06:15  Unpacking libopts25:amd64 (1:5.18.12-4) ...
09:06:15  Setting up libopts25:amd64 (1:5.18.12-4) ...
09:06:15  Setting up netbase (5.6) ...
09:06:15  Setting up ntp (1:4.2.8p12+dfsg-4+deb10u2) ...
09:06:15  
09:06:15  Configuration file '/etc/init.d/ntp'
09:06:15   ==> File on system created by you or by a script.
09:06:15   ==> File also in package provided by package maintainer.
09:06:15     What would you like to do about it ?  Your options are:
09:06:15      Y or I  : install the package maintainer's version
09:06:15      N or O  : keep your currently-installed version
09:06:15        D     : show the differences between the versions
09:06:15        Z     : start a shell to examine the situation
09:06:15   The default action is to keep your current version.
09:06:15  *** ntp (Y/I/N/O/D/Z) [default=N] ? dpkg: error processing package ntp (--configure):
09:06:15   end of file on stdin at conffile prompt
09:06:15  Processing triggers for libc-bin (2.28-10) ...
09:06:15  Errors were encountered while processing:
09:06:15   ntp