$php_errormsg was removed in PHP 8.0 (#4650)

* $php_errormsg was removed in PHP 8.0

See php/php-src@920b4b2
Use `&warn.deprecated.function-7-2-0.removed-8-0-0;` instead of
`&warn.deprecated.feature-7-2-0;`

* feature not function

Author: DanielEScherzer

language/predefined/variables/phperrormsg.xml

@@ -8,7 +8,7 @@
  </refnamediv>
 
  <refsynopsisdiv>
-  &warn.deprecated.feature-7-2-0;
+  &warn.deprecated.feature-7-2-0.removed-8-0-0;
   <simpara>
    Use <function>error_get_last</function> instead.
   </simpara>