specl: collect spec-files from subdirs correctly.
specl: collect spec-files from subdirs correctly.

* lib/specl/util.lua (files): table merging subdirectory files
into the array part of the master list overwrites previous
entries!  When we recurse, pass down the master list and append
new file names to that instead.

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

gvvaughan/specl