It's a little bit strange to have too suffixed flags keeping only two unsuffixed, unless removing suffix of all other flags. :-/
But suffix is very helpful when we are using many flags, because suffix help us to know what feature a flag belongs to, so it would be nice if we could rename it to MHD_USE_SUPPRESSED_DATE ("use suppressed date" makes sense) and MHD_USE_END_FLAG ("use end flag" makes sense too).
I had a problem in my project, it didn't compile it because a flag was renamed, luckily I checked the GIT log and found some flags renamed, so a major version should be released warning these last changes was done in the MHD interface.