Fix macros that were not properly surrounded by parens or braces.

src/backend/access/common/scankey.c

src/backend/access/index/indexam.c

src/backend/executor/nodeMergejoin.c

src/backend/optimizer/path/xfunc.c

src/backend/storage/buffer/freelist.c

src/backend/tcop/utility.c

src/backend/tioga/Arr_TgRecipe.h

src/backend/tioga/Varray.h

src/backend/utils/adt/date.c

src/backend/utils/adt/dt.c

src/backend/utils/cache/catcache.c

src/backend/utils/cache/relcache.c

src/backend/utils/mmgr/portalmem.c

src/backend/utils/sort/psort.c

src/bin/psql/psqlHelp.h

src/include/access/attnum.h

src/include/access/heapam.h

src/include/access/itup.h

src/include/c.h

src/include/executor/execdebug.h