This is the first in a series of commits to replace Heimdal with MIT KRB5. This first commit adds the WITH_MITKRB5/MK_MITKRB5 knob to src.opts.mk and its corresponding documentation in tools/build/options. The default is off.
The reason for adding this first is it permits me the luxury of adding support for MIT KRB5 using smaller commits. This allows for less daunting reviews. The intent is to add the contrib and crypto software to the tree without review while each individual change is small enough to be easily reviewed.
This change of and by itself will have no consequence to the existing tree or FreeBSD buildworld until the remaining commits are added.
The reason for this approach is I'd prefer getting this right the first time rather than having to go back and change things after people have left comments about any of the commits.
This is the first of many.