pgsql-server: Allow second and subsequent names in a qualified (dotted)

Log Message:
-----------
Allow second and subsequent names in a qualified (dotted) name to be
ColLabel instead of just ColId --- that is, any keyword can appear after
a dot and it will be taken as an identifier.  Fixes problems with names
that are okay as standalone function names but fail when qualified.

Modified Files:
--------------
    pgsql-server/src/backend/parser:
        gram.y (r2.473 -> r2.474)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/parser/gram.y.diff?r1=2.473&r2=2.474)