There are stale symlinks in db4-devel. IMHO cxx_{common,except}.h headers even if they weren't stale symlinks don't belong to /usr/include, they are db4 specific but don't have db anywhere in the name, as such they should only be present in db4/ directory if they are needed for something, or not at all.
Fixed in db-4.2.52-4. I entirely agree regarding /usr/include. Unfortunately, there is much busted software that does not have -I/usr/include/db4, hence /usr/include/db.h. db_cxx.h was a bug fix in the ancient past, the stale symlinks too.