cmake/common/* missing in source archives

[sgoth]

Hi!

The source archives seem to miss the cmake/common contents.
All the way from https://github.com/swift-nav/libsbp/archive/v3.4.2.tar.gz back to at least https://github.com/swift-nav/libsbp/archive/v3.1.1.tar.gz

[silverjam]

Apparently this is a limitation of GitHub's source archives: dear-github/dear-github#214 -- you can find the current code for our cmake modules here: https://github.com/swift-nav/cmake (these are generally backwards compatible so any version you pull should work)-- alternately you can clone everything with git including the cmake submodule with the --recursive switch:

git clone --recursive https://github.com/swift-nav/libsbp.git