Fix warnings in man page build

The changes in the CREATE POLICY man page from commit
87c2a17fee triggered a stylesheet bug that
created some warning messages and incorrect output.  This installs a
workaround.

Also improve the whitespace a bit so it looks better.

doc/src/sgml/ref/create_policy.sgml

@@ -445,8 +445,7 @@ CREATE POLICY <replaceable class="parameter">name</replaceable> ON <replaceable
       <row>
        <entry><command>INSERT ... RETURNING</command></entry>
        <entry>
-        New row
-        <footnote id="rls-select-priv">
+        New row <footnote id="rls-select-priv">
          <para>
           If read access is required to the existing or new row (for example,
           a <literal>WHERE</literal> or <literal>RETURNING</literal> clause
@@ -462,8 +461,7 @@ CREATE POLICY <replaceable class="parameter">name</replaceable> ON <replaceable
       <row>
        <entry><command>UPDATE</command></entry>
        <entry>
-        Existing &amp; new rows
-        <footnoteref linkend="rls-select-priv"/>
+        Existing &amp; new rows <footnoteref linkend="rls-select-priv"/>
        </entry>
        <entry>&mdash;</entry>
        <entry>Existing row</entry>
@@ -473,8 +471,7 @@ CREATE POLICY <replaceable class="parameter">name</replaceable> ON <replaceable
       <row>
        <entry><command>DELETE</command></entry>
        <entry>
-        Existing row
-        <footnoteref linkend="rls-select-priv"/>
+        Existing row <footnoteref linkend="rls-select-priv"/>
        </entry>
        <entry>&mdash;</entry>
        <entry>&mdash;</entry>

doc/src/sgml/stylesheet-man.xsl

@@ -191,6 +191,12 @@
   <xsl:template match="indexterm"/>
 
 
+<!-- https://github.com/docbook/xslt10-stylesheets/issues/59 -->
+<xsl:template match="a/sup">
+  <xsl:apply-templates/>
+</xsl:template>
+
+
 <!-- Gentext customization -->
 
 <!-- see http://www.sagehill.net/docbookxsl/CustomGentext.html -->