Cleanup various comparisons with the constant "true".

contrib/pg_upgrade/pg_upgrade.c

src/backend/access/gin/ginget.c

src/backend/access/gist/gistproc.c

src/backend/commands/sequence.c

src/backend/tsearch/regis.c

src/backend/utils/adt/geo_ops.c

src/backend/utils/adt/tsrank.c

src/backend/utils/adt/tsvector_op.c

src/bin/psql/print.c

src/interfaces/ecpg/ecpglib/connect.c

src/interfaces/ecpg/preproc/ecpg.addons