util/perl/OpenSSL/config.pm: Prefer POSIX::uname() over piping the command
util/perl/OpenSSL/config.pm: Prefer POSIX::uname() over piping the command

POSIX::uname() has the advantage to work on non-POSIX systems as well,
such as the Windows command prompt and VMS.

Reviewed-by: Tim Hudson <eb0be8e447f673b41b10eda09d63cd72526b0a42@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11230)

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