crypto: testmgr - enable CRYPTO_MANAGER when CRYPTO_SELFTESTS

crypto/testmgr.c is compiled only when CRYPTO_MANAGER is enabled.  To
make CRYPTO_SELFTESTS work as expected when CRYPTO_MANAGER doesn't get
enabled for another reason, automatically set CRYPTO_MANAGER to the
value of CRYPTO_ALGAPI when CRYPTO_SELFTESTS is enabled.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>