Avoid crud in tools directory

[AnyOldName3]

Some of the packages we use, in particular Boost and ICU, install large things we don't want in the tools directory. Hopefully, the archive could be a chunk smaller without it, especially once extracted.

[AnyOldName3]

It looks like we're explicitly requesting the ICU tools by installing icu instead of icu[core], so if we don't need those tools, that should be an easy fix.

[AnyOldName3]

I did an experiment to see what would happen if instead of using --x-all-installed, we passed the list of packages to export explicitly. It avoided packaging some GLU and OpenGL headers and .pc files, but that was the only difference. It still exported all the tools.