Move some things from builtins.h to new header files

contrib/bloom/blvalidate.c

contrib/citext/citext.c

contrib/dblink/dblink.c

contrib/fuzzystrmatch/fuzzystrmatch.c

contrib/pageinspect/btreefuncs.c

contrib/pageinspect/rawpage.c

contrib/pgrowlocks/pgrowlocks.c

contrib/pgstattuple/pgstatindex.c

contrib/pgstattuple/pgstattuple.c

contrib/postgres_fdw/option.c

contrib/tsearch2/tsearch2.c

contrib/unaccent/unaccent.c

src/backend/access/brin/brin_validate.c

src/backend/access/gin/ginvalidate.c

src/backend/access/gist/gistvalidate.c

src/backend/access/hash/hashvalidate.c

src/backend/access/nbtree/nbtvalidate.c

src/backend/access/spgist/spgtextproc.c

src/backend/access/spgist/spgvalidate.c

src/backend/catalog/namespace.c