pgsql: Prevent BLCKSZ < 1024, and have initdb test shared buffers based

Log Message:
-----------
Prevent BLCKSZ < 1024, and have initdb test shared buffers based on the
BLCKSZ value.

Modified Files:
--------------
pgsql/src/bin/initdb:
initdb.c (r1.133 -> r1.134)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/initdb/initdb.c.diff?r1=1.133&amp;r2=1.134)
pgsql/src/include:
pg_config_manual.h (r1.24 -> r1.25)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/pg_config_manual.h.diff?r1=1.24&amp;r2=1.25)