tests: skip broken automake wrapper on MirBSD
On a fresh default install, MirBSD ships with an automake wrapper
script that has bad behavior:
$ automake --version; echo $?
Provide an AUTOMAKE_VERSION environment variable, please
0
* tests/tools.at (autom4te preselections): Skip, rather than fail,
if 'automake --version' succeeds without printing a version when
an environment variable is not set.
* tests/torture.at (Configuring subdirectories)
(Unusual Automake input files): Likewise.
Signed-off-by: Eric Blake <eblake@redhat.com>