pgsql: Change error messages to print the physical path, like

Log Message:
-----------
Change error messages to print the physical path, like
"base/11517/3767_fsm", instead of symbolic names like "1663/11517/3767/1",
per Alvaro's suggestion. I didn't change the messages in the higher-level
index, heap and FSM routines, though, where the fork is implicit.

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        xact.c (r1.266 -> r1.267)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c?r1=1.266&r2=1.267)
        xlogutils.c (r1.61 -> r1.62)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlogutils.c?r1=1.61&r2=1.62)
    pgsql/src/backend/storage/buffer:
        bufmgr.c (r1.240 -> r1.241)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/buffer/bufmgr.c?r1=1.240&r2=1.241)
        localbuf.c (r1.81 -> r1.82)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/buffer/localbuf.c?r1=1.81&r2=1.82)
    pgsql/src/backend/storage/smgr:
        md.c (r1.139 -> r1.140)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/smgr/md.c?r1=1.139&r2=1.140)
        smgr.c (r1.112 -> r1.113)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/smgr/smgr.c?r1=1.112&r2=1.113)