Fix the return type of NativeCrypto_X509_check_issued.
Fix the return type of NativeCrypto_X509_check_issued.

The X509_check_issued C function returns one of the X509_V_* constants,
where X509_V_OK is zero. The JNI C++ wrapper casts that directly to a
jboolean, which is uint8_t and will likely do the wrong thing if
BoringSSL ever allocates a multiple of 256 as a constant.

The NativeCrypto type signature and call site then go back to returning
int and check the result with == 0. Fix the JNI C++ wrapper to match
both what BoringSSL and the NativeCrypto class are actually expecting.

google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt,google/conscrypt