appveyor.yml: omit makedepend step.
appveyor.yml: omit makedepend step.

makedepend makes lesser sense in a throw-away build like CI, but
it spares some computational time, because with MSVC it takes
separate per-file compiler invocation.

Reviewed-by: Richard Levitte <5fb523282dd7956571c80524edc2dccfa0bd8234@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5452)

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