specs: speed up most slow tests by three orders of magnitude.
specs: speed up most slow tests by three orders of magnitude.

* specs/mkrockspecs_spec.yaml: The gnulib tree is huge and
deep, so using os.execute to traverse all of it with subshells
is incredibly slow.  Only the last spec needs it, the rest are
much improved by putting the test fils in a subdirectory and
traversing only that.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

gvvaughan/slingshot