pgsql: Allow CREATE INDEX CONCURRENTLY to disregard transactions in

Log Message:
-----------
Allow CREATE INDEX CONCURRENTLY to disregard transactions in other
databases, per gripe from hubert depesz lubaczewski.  Patch from
Simon Riggs.

Modified Files:
--------------
    pgsql/doc/src/sgml/ref:
        create_index.sgml (r1.63 -> r1.64)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_index.sgml?r1=1.63&r2=1.64)
    pgsql/src/backend/commands:
        indexcmds.c (r1.163 -> r1.164)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/indexcmds.c?r1=1.163&r2=1.164)
    pgsql/src/backend/storage/ipc:
        procarray.c (r1.30 -> r1.31)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/procarray.c?r1=1.30&r2=1.31)
    pgsql/src/include/storage:
        procarray.h (r1.15 -> r1.16)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/procarray.h?r1=1.15&r2=1.16)