configury: support non-autotool LuaRocks installation.

* slingshot: Sync with upstream.
* local.mk (mkrockspecs_args): Add --module-dir so that latest
mkrockspecs will use the LuaRocks builtin build.type.
* std/std.lua.in, std/base.lua, std/debug_ext.lua,
std/debug_init.lua, std/functional.lua, std/getopt.lua,
std/io_ext.lua, std/list.lua, std/math_ext.lua, std/modules.lua,
std/oject.lua, std/package_ext.lua, std/set.lua,
std/strbuf.lua, std/strict.lua, std/string_ext.lua,
std/table_ext.lua, std/tree.lua: Move from here...
* lib/std.lua.in, lib/std/base.lua, lib/std/debug_ext.lua,
lib/std/debug_init.lua, lib/std/functional.lua, lib/std/getopt.lua,
lib/std/io_ext.lua, lib/std/list.lua, lib/std/math_ext.lua,
lib/std/modules.lua, lib/std/oject.lua, lib/std/package_ext.lua,
lib/std/set.lua, lib/std/strbuf.lua, lib/std/strict.lua,
lib/std/string_ext.lua, lib/std/table_ext.lua, lib/std/tree.lua:
...to here.
* local.mk (std_path): Adjust.
* std/.gitignore: Remove. Consolidate into...
* .gitignore: ...here.
* std/std.mk: Remove. Consolidate into...
* local.mk: ...hore.
* NEWS: Update.

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