pgsql: Don't convert the man page names to lower case, so that the .so

Log Message:
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Don't convert the man page names to lower case, so that the .so links work.
This is pretty much a workaround for incomplete tools, but having the man
page names in upper case looks more natural anyway.

Modified Files:
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    pgsql/doc/src/sgml:
        Makefile (r1.115 -> r1.116)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/Makefile?r1=1.115&r2=1.116)