mail/bincimap failed to build:
https://lists.freebsd.org/pipermail/freebsd-pkg-fallout/Week-of-Mon-20180806/854178.html
https://lists.freebsd.org/pipermail/freebsd-pkg-fallout/Week-of-Mon-20180806/854566.html
https://lists.freebsd.org/pipermail/freebsd-pkg-fallout/Week-of-Mon-20180806/854679.html
Proposed commit log message:
```
mail/bincimap: Fix build with Clang 6.0.0
Reviewed_by: koobs
Approved by: koobs (mentor)
Differential_Revision: D16658
```