This should decrease the number of allocations before main is entered
significantly, but complicates the code somewhat in return.
Assuming I used `massif` right, doing just `SelfTest --list-tests`
went from 929 allocations at "Remove gcc-4.9 from the travis builds"
(2 commits up), to 614 allocations with this commit.
Now a `TEST_CASE` macro should create a single TestCaseInfo and then
it should never be copied around. This, together with latter changes,
should significantly decrease the number of allocations made before
`main` is even entered.