pgsql: Since doc/src/sgml already builds the HTML docs twice to resolve

Log Message:
-----------
Since doc/src/sgml already builds the HTML docs twice to resolve index
entries, we don't have to do two builds here as well.

Modified Files:
--------------
pgsql/doc/src:
Makefile (r1.34 -> r1.35)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/Makefile?r1=1.34&r2=1.35)