regexec.c: Use new macros instead of swashes

regexec.c: Use new macros instead of swashes

A previous commit has caused macros to be generated that will match
Unicode code points of interest to the \X algorithm.  This patch uses
them.  This speeds up modern Korean processing by 15%.

Together with recent previous commits, the throughput of modern Korean
under \X has more than doubled, and is now comparable to other
languages (which have increased themselved by 35%)