#573 Tests failing on FreeBSD

[Ed Maste]

See Cirrus-CI results at http://cirrus-ci.com/github/elftoolchain/elftoolchain
Most recent at time of submission: http://cirrus-ci.com/build/5232292505583616
debian_stable job passes, freebsd_11 job fails with:

===> test/libelf/tset/common (all)
_E=`echo msb | tr '[a-z]' '[A-Z]'`; _C=`echo 32 | tr '[a-z]' '[A-Z]'`;  cat /tmp/cirrus-ci-build/test/libelf/tset/common/check_elf.yaml | sed -e "s/ELFDATANONE/ELFDATA2${_E}/g"  -e "s/ELFCLASSNONE/ELFCLASS${_C}/g" |  /tmp/cirrus-ci-build/test/libelf/tset/bin/elfc -o check_elf.msb32
/tmp/cirrus-ci-build/test/libelf/tset/bin/elfc:1610: YAMLLoadWarning: calling yaml.load() without Loader=... is deprecated, as the default Loader is unsafe. Please read https://msg.pyyaml.org/load for full details.
  elf = make_elf(yaml.load(stream))
Usage: elfc [options] [input-file]
elfc: error: cannot parse stream: could not determine a constructor for the tag '!Ehdr'
  in "<stdin>", line 4, column 7
*** Error code 2
Stop.

[Joseph Koshy]

Seems to be https://github.com/yaml/pyyaml/issues/266.

[Joseph Koshy]

Should be fixed by [r3775].