pgsql: Add code to pg_dump to use E'' strings when backslashes are used

Log Message:
-----------
Add code to pg_dump to use E'' strings when backslashes are used in dump
files.

Modified Files:
--------------
pgsql/src/bin/pg_dump:
dumputils.c (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/dumputils.c.diff?r1=1.17&r2=1.18)
pg_backup_db.c (r1.62 -> r1.63)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_backup_db.c.diff?r1=1.62&r2=1.63)
pg_dump.c (r1.411 -> r1.412)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.c.diff?r1=1.411&r2=1.412)