When --enable-valgrind is used, this commit adds support for running the
perl FKO built-in tests (in the t/ directory) under the CPAN
Test::Valgrind module. A check is performed to see whether
Test::Valgrind is install before attempting to use it. Any 'fko_'
function that shows up under the test output is flagged and causes the
test-suite test to fail.