For MIT Kerberos, MK_GSSAPI has no meaning: GSSAPI is a required part of
Kerberos and is always built if MK_KERBEROS is enabled. Backport this
behaviour to Heimdal so it works the same way.
While here, change Heimdal's libcom_err and compile_et to be selected by
MK_KERBEROS, not MK_KERBEROS_SUPPORT, since these are part of Kerberos
and third-party users might need it even if Kerberos support is disabled
in the base system. This means MK_KERBEROS_SUPPORT installs the same
files with both MIT and Heimdal.
Reviewed by: cy
Differential Revision: https://reviews.freebsd.org/D51859
Lexi Winter
dc5ba6b8b4