Log Message:
cppunit: update to 1.15.1.

  New in CppUnit 1.15.1:
  ---------------------

* Portability:

  - Fix Wdefaulted-function-deleted warning with clang

  - Remove old Visual Studio project files

  New in CppUnit 1.15.0:
  ---------------------

  - Report (un)signed character as intergers

  - add CPPUNIT_TEST_FIXTURE()

  - add message_to_string trait to allow custom string formatters

* Portability:
  - Fix build with gcc 9

  - Fix various compiler warnings