Revert forcing use of single-parameter static_assert()

Some clang versions define static_assert as a macro apparently, so we cannot
redefine it...

This reverts commit 94bfea0ce6a7b4d5641c198d50751748a353df11.
This reverts commit 4e62627831e7457ed60ff87712570065b14b200a.
23 files changed