* tests/test-stdbool-c++.cc: Don't include <stdbool.h> if TEST_STDBOOL_H
is not defined. Add a couple of simple tests, from test-stdbool.c.
* tests/test-stdbool-c99-c++.cc: New file.
* modules/stdbool-c99-c++-tests: New file, based on
modules/stdbool-c++-tests.
* modules/stdbool-c99-tests (Depends-on): Add stdbool-c99-c++-tests.
Remove stdbool-c++-tests.
* modules/stdbool-tests (Depends-on): Add stdbool-c++-tests.