test: introduce (mini) unit test framework

Lightweight unit testing framework, providing a structured way to define,
execute, and report tests. It includes a central test registry, a flexible
command-line argument parser of the form "-key=value" (facilitating future
framework extensions), ability to run tests in parallel and accumulated
test time logging reports.

So far the supported command-line args are:
- "-jobs=<num>" to specify the number of parallel workers.
- "-seed=<hex>" to specify the context seed (random if not set).
- "-iterations=<value>" to specify the number of iterations.

Compatibility Note:
To stay compatible with previous versions, the framework also supports
the two original positional arguments: the iterations count and the
RNG seed (in that order).

Author: furszy

Makefile.am

@@ -45,6 +45,8 @@ noinst_HEADERS += src/precomputed_ecmult.h
 noinst_HEADERS += src/precomputed_ecmult_gen.h
 noinst_HEADERS += src/assumptions.h
 noinst_HEADERS += src/checkmem.h
+noinst_HEADERS += src/unit_test.h
+noinst_HEADERS += src/unit_test.c
 noinst_HEADERS += src/testutil.h
 noinst_HEADERS += src/util.h
 noinst_HEADERS += src/util_local_visibility.h