Make CRYPTO_num_locks() return 1
Make CRYPTO_num_locks() return 1

malloc(0) might return NULL and code for the old callbacks might fail,
instead just say they should allocate 1 entry.

Reviewed-by: Matt Caswell <matt@openssl.org>

GH: #1266

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl