pgsql: Add back #include <time.h> in a couple of files that seem to need

Log Message:
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Add back #include <time.h> in a couple of files that seem to need it
on Linux.

Modified Files:
--------------
pgsql/src/backend/bootstrap:
bootstrap.c (r1.238 -> r1.239)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/bootstrap/bootstrap.c?r1=1.238&r2=1.239)
pgsql/src/backend/tcop:
postgres.c (r1.542 -> r1.543)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c?r1=1.542&r2=1.543)