Change to crypto_primitives host function signature and semantics.

[larryk85]

For the host functions:

alt_bn128_add, alt_bn128_mul, alt_bn128_pair, mod_exp, blake2_f, and k1_recover the return values have changed.

Before 0 represented success and 1 represented failure. Now, 0 still represents success but -1 represents failure.

This is done to allow for tri-state return values and specifically for alt_bn128_pair.

The new signature for alt_bn128_pair should be int32_t alt_bn128_pair(const char* bytes, uint32_t length); with the return value capturing whether it was a failure or true/false.

On failure it will return -1, 1 on false and 0 if true and successful.

In addition there are a couple of uses of bool in the new function signatures for blake2_f and sha3. These need to be changed to a fixed size type (preferably int32_t).

Note that since this changes the behavior of the CRYPTO_PRIMITIVES protocol feature without introducing a new protocol feature, the CRYPTO_PRIMITIVES protocol feature of 3.1.0-rc1 should not be used. To reduce confusion among peers who may still use 3.1.0-rc1 in a network with later releases, the feature description of the CRYPTO_PRIMITIVES protocol feature should be changed so that it ends up having a new protocol feature digest.