cm_cxx_features: Ignore Clang unused-argument warnings
Filter out -Wunused-command-line-argument
warnings from Clang (that
can be caused by user-specified flags) so that they do not break our
checks for C++ feature availability.
This extends !1286 (merged).
Original Description
When building a cmake RPM package using clang on openEuler, the compilation fails due to the "Wunused-command-line-argument" warning. However, this warning does not indicate an unsupported feature.
Topic-rename: cxx-checks-tolerate-unused-arguments
Edited by Brad King