Log Message:
Omit "-MT $@" from generated make rules, as it breaks SunPro builds and
"-o $@" is already sufficient.

Also for SunPro, set OPENSSL_HOST.SunOS-x86_64=solaris64-x86_64-cc
(that's cc, not gcc) to avoid this error linking libcrypto.so:

    cc: Warning: Option --libgcc passed to ld, if ld is invoked,
    ignored otherwise
    cc: No valid input files specified, no output generated

"make package" succeeds on:

- Solaris 11 with "Studio 12.6 Sun C 5.15"
- Tribblix m25.1 with pkgsrc gcc7
- CentOS 7 with pkgsrc gcc7
- FreeBSD 13 with system clang
- OpenBSD 7.0 with system clang
- NetBSD 9.2 and -current with system gcc
- CentOS 8 with system gcc
- Debian 11, 10, 9 with system gcc
- Devuan 4 with system gcc
- Ubuntu 21, 18, 16, 14 with system gcc
- Void with system gcc
- Gentoo with system gcc