matchers: error matcher no longer requires reversed arguments.

* specs/matchers_spec.yaml (error matcher): Specify all the
behaviours of a normal argument order `should_error` based
expectation.
* specs/speclc_spec.yaml (it expands the expect macro): Specify
the format of expanded expect calls.
* build-aux/speclc.in (dump_example): Implement it.  Use a
LuaMacro to inject a pcall into the expect expression.
* specl-rockspec.lua (dependencies): Add luamacro >= 2.2.0.
* specl/specl.lua (compile_example): Use the same LuaMacro to
inject a pcall into compiled YAML chunks.
(run_examples): Rename expect to _expect in the sandbox env to
match the name in the expanded expect pcall.
* specl/matchers.c (expect): New `ok` parameter to capture the
pcall status.  Pass `ok` to the selected matcher handler.
(matchers.error): Require arguments in the same order as the
other matchers, plus a new `ok` parameter.
* specs/matchers_spec.yaml: Fill in the remaining specifications
for all currently implemnted matchers.

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