pgsql: Add --with-libxslt configure option

Log Message:
-----------
Add --with-libxslt configure option

Modified Files:
--------------
pgsql:
configure (r1.543 -> r1.544)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/configure.diff?r1=1.543&r2=1.544)
configure.in (r1.510 -> r1.511)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/configure.in.diff?r1=1.510&r2=1.511)
pgsql/contrib:
Makefile (r1.73 -> r1.74)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/Makefile.diff?r1=1.73&r2=1.74)
pgsql/src:
Makefile.global.in (r1.234 -> r1.235)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/Makefile.global.in.diff?r1=1.234&r2=1.235)
pgsql/src/include:
pg_config.h.in (r1.115 -> r1.116)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/pg_config.h.in.diff?r1=1.115&r2=1.116)