doc: Whitespace fixes in man pages

doc/src/sgml/ref/alter_index.sgml

@@ -285,8 +285,7 @@ REINDEX INDEX distributors;
 <programlisting>
 CREATE INDEX coord_idx ON measured (x, y, (z + t));
 ALTER INDEX coord_idx ALTER COLUMN 3 SET STATISTICS 1000;
-</programlisting>
+</programlisting></para>
-  </para>
 
  </refsect1>
 

doc/src/sgml/ref/alter_table.sgml

@@ -132,7 +132,6 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
 <phrase><replaceable class="parameter">exclude_element</replaceable> in an <literal>EXCLUDE</literal> constraint is:</phrase>
 
 { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ <replaceable class="parameter">opclass</replaceable> ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ]
-
 </synopsis>
  </refsynopsisdiv>
 

doc/src/sgml/ref/create_policy.sgml

@@ -557,8 +557,7 @@ AND
   OR
   ...
 )
-</programlisting>
+</programlisting></para>
-   </para>
 
   </refsect2>
  </refsect1>

doc/src/sgml/ref/pg_ctl-ref.sgml

@@ -681,8 +681,7 @@ PostgreSQL documentation
 <computeroutput>
 pg_ctl: server is running (PID: 13718)
 /usr/local/pgsql/bin/postgres "-D" "/usr/local/pgsql/data" "-p" "5433" "-B" "128"
-</computeroutput>
+</computeroutput></screen>
-</screen>
     The second line is the command that would be invoked in restart mode.
    </para>
   </refsect2>