security/heimdal: Fix build
Three problems were discovered when building under poudriere or in
a clean jail.
- Python is now a prerequisite.
- liblockfile is now needed.
- clang-format is needed for asn1_compile. Unfortunately the base llvm does not install clang-format so we need install $LLVM_DEFAULT to get this file.
PR: 267814
Reported by: many
Fixes: 83f79ba0e0ca
MFH: 2022Q4