fix(bzrtp): disable new gcc 8 -Wcast-function-type warnings (FIXME in the future)

Status Job ID Name Coverage
  External
passed jenkins

00:56:47

passed jenkins(Centos6)

00:00:12

passed jenkins(Centos7)

00:00:10

passed jenkins(Debian7)

00:00:14

passed jenkins(Debian8)

00:01:08

passed jenkins(Mac)

00:03:41

passed jenkins

00:00:27

passed jenkins

00:55:43

passed jenkins

00:00:15

passed jenkins(Centos6)

00:00:11

passed jenkins(Centos6)

00:00:11

passed jenkins(Centos6)

00:00:11

passed jenkins(Centos7)

00:00:10

passed jenkins(Centos7)

00:00:10

passed jenkins(Debian7)

00:00:14

passed jenkins(Debian7)

00:00:12

passed jenkins(Debian7)

00:00:13

passed jenkins(Debian8)

00:00:13

passed jenkins(Debian8)

00:00:13

passed jenkins(Debian8)

00:00:16

passed jenkins(Mac)

00:01:37

passed jenkins(Mac)

00:01:00

passed jenkins(Mac)

00:00:55