headerscheck and cpluspluscheck should skip the recently-added
cmdtaglist.h header, since (like kwlist.h and some other similarly-
designed headers) it's not meant to be included standalone.

evtcache.h was missing an #include to support its usage of Bitmapset.

typecmds.h was missing an #include to support its usage of ParseState.

The first two of these were evidently oversights in commit 2f966131.
I didn't track down exactly which change broke typecmds.h, but it
must have been some rearrangement in one of its existing inclusions,
because it's referenced ParseState for quite a long time and there
were not complaints from these checking programs before.