Add some extra Cygwin targets as aliases for Cygwin-x86

Cygwin was used for x86 before, so let's keep it around for those who
still use it (it make Configure reconf possible).
Cygwin-i[3456]86 for those that might generate and pass a target name
directly to Configure.

Reviewed-by: Rich Salz <rsalz@openssl.org>