[skip-revcheck] Remove xi:fallback, partial fix for doc-it (#4357)

Co-authored-by: André L F S Bacci <[email protected]>

Author: alfsb

reference/gmp/gmp/construct.xml

@@ -18,9 +18,7 @@
  </refsect1>
 
  <refsect1 role="parameters">
-  <xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('function.gmp-init')/db:refsect1[@role='parameters']/*)">
-   <xi:fallback/>
-  </xi:include>
+  <xi:include xpointer="xmlns(db=http://docbook.org/ns/docbook) xpointer(id('function.gmp-init')/db:refsect1[@role='parameters']/*)"/>
  </refsect1>
 
  <refsect1 role="seealso">