The 9.16 version of ./configure calls bin/tests/system/cleanall.sh
unless --without-make-clean is used. The cleanall.sh script then
includes bin/tests/system/conf.sh, which includes
bin/tests/system/conf.sh.common. At that point, dnssec-keygen which is
used to detect algorithm support isn't compiled, so it can't be used.
More importantly, algorithm selection for system tests during the
./configure phase is irrelevant, so it can be safely skipped.
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