djgpp: Inherit config from BASE_unix
djgpp: Inherit config from BASE_unix

Build failed on djgpp due to missing config vars 'AR' and 'ARFLAGS'.
Additionally, '-lz' was not added to 'lflags' when zlib support was
enabled.  Inheriting configuration variables from BASE_unix solves both
these issues.

CLA: trivial

Reviewed-by: Richard Levitte <5fb523282dd7956571c80524edc2dccfa0bd8234@openssl.org>
Reviewed-by: Tomas Mraz <2bc6038c3dfca09b2da23c8b6da8ba884dc2dcc2@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19274)

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