meson: Add unit test framework

This commit also adds the first unit test. The unit test compares the
phonetic map generated by the Python and by the C implementation and
fails if the generated maps are different.

tests/meson.build

@@ -0,0 +1,12 @@
+
+_phogen_map_c = PHOGEN_MAP_EXE.full_path()
+_phogen_map_py = meson.source_root() / '@0@'.format(PHOGEN_MAP_PY[0])
+_word_list = meson.source_root() / '@0@'.format(PHOGEN_WORD_LIST[0])
+
+test('test_phogen_map',
+    find_program('test_phogen_map'),
+    env : ['PHOGEN_MAP_C=@0@'.format(_phogen_map_c),
+           'PHOGEN_MAP_PY=@0@'.format(_phogen_map_py),
+           'PHOGEN_WORD_LIST=@0@'.format(_word_list)])
+
+