Replacing Boost dependency in ft-testing with explicit constructor deletion?

[Dominik Röttsches]

Hei all,

We're considering running some of the FreeType fuzzers as part of the internal Chromium fuzzing as well. In that setup, we have a different environment than for oss-fuzz and we can't have a Boost dependency. 

To that end, I filed a PR in https://github.com/freetype/freetype2-testing/pull/87 to remove the Boost dependency which was mainly used to mark the helper classes as non-copyable. I've replaced the usage of Boost with explicit constructor/copy-constructor deletions. 

I'd be happy if I could get a review and if we could merge the CL.

I have one more fix for some signed/unsigned comparison and other small warning fixes https://github.com/freetype/freetype2-testing/pull/88 - and I'll have one more PR soon to make the dependency on libarchive optional.

Hope this change looks good - 

Dominik