Fix incorrect comment in hba.h

Fix incorrect comment in hba.h

A comment in hba.h mentioned that AuthTokens are used when building the
IdentLines from pg_ident.conf, but since 8fea868 that has added support
of regexps for databases and roles in pg_hba.conf, it is also the case
of HBA files.  This refreshes the comment to refer to both HBA and ident
files.

Issue spotted while going through a different patch.