pgsql-server: Include c.h instead of postgres.h in files that need to be

Log Message:
-----------
Include c.h instead of postgres.h in files that need to be usable in
both frontend and backend. Per Andreas Pflug.

Modified Files:
--------------
pgsql-server/src/port:
getopt.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/getopt.c.diff?r1=1.5&r2=1.6)
getrusage.c (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/getrusage.c.diff?r1=1.4&r2=1.5)
gettimeofday.c (r1.4 -> r1.5)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/gettimeofday.c.diff?r1=1.4&r2=1.5)
kill.c (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/kill.c.diff?r1=1.1&r2=1.2)
noblock.c (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/noblock.c.diff?r1=1.1&r2=1.2)
pgsleep.c (r1.3 -> r1.4)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/pgsleep.c.diff?r1=1.3&r2=1.4)
pgstrcasecmp.c (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/pgstrcasecmp.c.diff?r1=1.1&r2=1.2)
pipe.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/pipe.c.diff?r1=1.5&r2=1.6)
sprompt.c (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/sprompt.c.diff?r1=1.5&r2=1.6)
thread.c (r1.22 -> r1.23)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/port/thread.c.diff?r1=1.22&r2=1.23)