Change the signature of rm_desc so that it's passed a XLogRecord.

contrib/pg_xlogdump/pg_xlogdump.c

contrib/pg_xlogdump/rmgrdesc.h

src/backend/access/rmgrdesc/clogdesc.c

src/backend/access/rmgrdesc/dbasedesc.c

src/backend/access/rmgrdesc/gindesc.c

src/backend/access/rmgrdesc/gistdesc.c

src/backend/access/rmgrdesc/hashdesc.c

src/backend/access/rmgrdesc/heapdesc.c

src/backend/access/rmgrdesc/mxactdesc.c

src/backend/access/rmgrdesc/nbtdesc.c

src/backend/access/rmgrdesc/relmapdesc.c

src/backend/access/rmgrdesc/seqdesc.c

src/backend/access/rmgrdesc/smgrdesc.c

src/backend/access/rmgrdesc/spgdesc.c

src/backend/access/rmgrdesc/standbydesc.c

src/backend/access/rmgrdesc/tblspcdesc.c

src/backend/access/rmgrdesc/xactdesc.c

src/backend/access/rmgrdesc/xlogdesc.c

src/backend/access/transam/xlog.c

src/include/access/clog.h