Migrate to kselftest harness. Use a fixture test with enclave initialized
and de-initialized for each of the existing three tests, in other words:
1. One FIXTURE() for managing the enclave life-cycle.
2. Three TEST_F()'s, one for each test case.
This gives a leaps better reporting than before. Here's an example
transcript:
TAP version 13
1..3
0x0000000000000000 0x0000000000002000 0x03
0x0000000000002000 0x0000000000001000 0x05
0x0000000000003000 0x0000000000003000 0x03
ok 1 enclave.unclobbered_vdso
0x0000000000000000 0x0000000000002000 0x03
0x0000000000002000 0x0000000000001000 0x05
0x0000000000003000 0x0000000000003000 0x03
ok 2 enclave.clobbered_vdso
0x0000000000000000 0x0000000000002000 0x03
0x0000000000002000 0x0000000000001000 0x05
0x0000000000003000 0x0000000000003000 0x03
ok 3 enclave.clobbered_vdso_and_user_function