build-sys: Add support for --disable-tests to disable tests

Add support for --disable-tests to disable the tests and the checking
for tools that only need to be installed for the tests. Keep the tests
enabled as default as it was before.

Resolves: https://github.com/stefanberger/swtpm/issues/843
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
2 files changed