pgsql: Add GUC log_lock_waits to log long wait times.

Log Message:
-----------
Add GUC log_lock_waits to log long wait times.

Simon Riggs

Modified Files:
--------------
    pgsql/doc/src/sgml:
        config.sgml (r1.113 -> r1.114)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml.diff?r1=1.113&r2=1.114)
    pgsql/src/backend/storage/lmgr:
        deadlock.c (r1.44 -> r1.45)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/deadlock.c.diff?r1=1.44&r2=1.45)
        proc.c (r1.184 -> r1.185)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/lmgr/proc.c.diff?r1=1.184&r2=1.185)
    pgsql/src/backend/utils/misc:
        guc.c (r1.377 -> r1.378)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c.diff?r1=1.377&r2=1.378)
        postgresql.conf.sample (r1.210 -> r1.211)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/postgresql.conf.sample.diff?r1=1.210&r2=1.211)
    pgsql/src/include/storage:
        lock.h (r1.103 -> r1.104)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/lock.h.diff?r1=1.103&r2=1.104)
        proc.h (r1.94 -> r1.95)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/proc.h.diff?r1=1.94&r2=1.95)