Add a way to skip submodule tests

[matthiasclasen]

My project builds with a bunch of submodules, but that doesn't mean that I need or want to run all the subprojects' tests every time I run meson test.

Specifying all my subprojects testsuites in --no-suite arguments is entirely impractical.

[eli-schwartz]

The obvious way to do this would be to somehow specify the primary project as the suite. I can't recall off the top of my head if this works but can you try specifying the project name as the suite? It may work even though it's not a subproject.

[matthiasclasen]

Ah, that seems to work, thanks.

[eli-schwartz]

OK, great. :) Thanks for the confirmation.