Fix AppVeyor/VC build failure

..\test\asn1_internal_test.c(96): warning C4113: 'int (__cdecl *)()'
differs in parameter lists from 'int (__cdecl *)(void)'

Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4744)