Does Clang.jl have an option to skip static functions?

[sloede]

Related to #267, but recently resurfaced in trixi-framework/P4est.jl#99. We know that it is not possible to make static functions callable from Julia (at least not trivially; since that would either require source-to-source translation or modifying the original library). However, it would be great if we had a mechanism to prevent them from being included in the generated Julia API.

cc @ranocha @Blumenkranz