CMake bug fix: didn't install zstdless and zstdgrep.

[LeeYoung624]

CMake bug fix: CMake didn't install zstdless and zstdgrep.

I mess up the last PR#1625 and create a new PR here.
Really sorry about this. @felixhandte

[Mno-hime]

The commit itself might be improved, I suggest something like this:

Install zstdless and zstdgrep as 'programs'

Closes #1503.

[LeeYoung624]

@Mno-hime Do you mean that the commit message should be more specific?

[Mno-hime]

Yes, subject of the pull request is ok, but the commit message can be more specific about what's happening in the commit.

[LeeYoung624]

Sure, I think you are right. Thank you so much @Mno-hime .

[felixhandte]

Thanks for fixing the stack! I have one last suggested change: it would be cleaner if you could use ${PROGRAMS_DIR}/ rather than ${CMAKE_SOURCE_DIR}/../../programs/. Will that work? And if so, can you switch to that?

Thanks!

[LeeYoung624]

Sure. I have switched to this.

[Cyan4973]

Thanks @LeeYoung624