Configure: fix Mac OS X builds that still require makedepend

Earlier Apple Xcode compilers, e.g. one targeting Mac OS X 10.7, don't
support dependency generation and one still has to use makedepend.  It's
unclear when it was fixed, but all clang-based Apple compilers seem to
support -M options.

Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6073)