minicom: security bump to version 2.7.1

minicom: security bump to version 2.7.1

Fixes CVE-2017-7467 - minicom and prl-vzvncserver vt100.c escparms[] buffer
overflow.

For more details about the issue, see the nice writeup on oss-security:

http://www.openwall.com/lists/oss-security/2017/04/18/5

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>