tcpdump: drop unneeded security patches

Version 4.7.4 of tcpdump is not vulnerable to these issues according to:

   https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8767
   https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8768
   https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-8769



The tcpdump commit log seems to indicate that these issues were fixes in a
different way in the following commits:

CVE-2014-8767: 4038f83ebf654804829b258dde5e0a508c1c2003
CVE-2014-8768: 9255c9b05b0a04b8d89739b3efcb9f393a617fe9
CVE-2014-8769: 9ed7ddb48fd557dc993e73f22a50dda6cedf4df7

Just drop these patches.

Cc: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>