pgsql: Adjust initialization sequence for timezone_abbreviations so that

Log Message:
-----------
Adjust initialization sequence for timezone_abbreviations so that
it's handled just about like timezone; in particular, don't try
to read anything during InitializeGUCOptions. Should solve current
startup failure on Windows, and avoid wasted cycles if a nondefault
setting is specified in postgresql.conf too. Possibly we need to
think about a more general solution for handling 'expensive to set'
GUC options.

Modified Files:
--------------
pgsql/src/backend/bootstrap:
bootstrap.c (r1.220 -> r1.221)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/bootstrap/bootstrap.c.diff?r1=1.220&r2=1.221)
pgsql/src/backend/postmaster:
postmaster.c (r1.496 -> r1.497)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/postmaster/postmaster.c.diff?r1=1.496&r2=1.497)
pgsql/src/backend/tcop:
postgres.c (r1.492 -> r1.493)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.492&r2=1.493)
pgsql/src/backend/utils/misc:
guc.c (r1.332 -> r1.333)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/guc.c.diff?r1=1.332&r2=1.333)
pgsql/src/include/utils:
guc.h (r1.70 -> r1.71)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/guc.h.diff?r1=1.70&r2=1.71)