pkglint checks:

- WARN: PLIST:6: Manual page missing for bin/shrink_width
- WARN: PLIST:8: Manual page missing for bin/vips-8.1

Makefile:

- Add in Tiff buildlink? Also, should these be includes or DEPENDS, I'm still not sure.

options.mk:

- Should add in all the optional dependencies.

Other files:

- Add a buildlink file, since vips is primarily a library to be used by other things.
