Обсуждение: pgsql: Make stats_temp_directory PGC_SIGHUP, and document how it may

Log Message:
-----------
Make stats_temp_directory PGC_SIGHUP, and document how it may cause a temporary
"outage" of the statistics views.

This requires making the stats collector respond to SIGHUP, like the other
utility processes already did.

Modified Files:
--------------
    pgsql/src/backend/utils/misc:
        guc.c (r1.469 -> r1.470)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c?r1=1.469&r2=1.470)
    pgsql/doc/src/sgml:
        config.sgml (r1.187 -> r1.188)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/config.sgml?r1=1.187&r2=1.188)
    pgsql/src/backend/postmaster:
        pgstat.c (r1.179 -> r1.180)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/pgstat.c?r1=1.179&r2=1.180)
        postmaster.c (r1.561 -> r1.562)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/postmaster.c?r1=1.561&r2=1.562)