Additional fix for 18201 XML: ExtractValue works even if the xml fragment is not well-formed xml

Changing error number

mysql-test/r/xml.result

@@ -640,32 +640,32 @@ select extractValue('<a>a','/a');
 extractValue('<a>a','/a')
 NULL
 Warnings:
-Warning	1504	Incorrect XML value: 'parse error at line 1 pos 5: unexpected END-OF-INPUT'
+Warning	1512	Incorrect XML value: 'parse error at line 1 pos 5: unexpected END-OF-INPUT'
 select extractValue('<a>a<','/a');
 extractValue('<a>a<','/a')
 NULL
 Warnings:
-Warning	1504	Incorrect XML value: 'parse error at line 1 pos 6: END-OF-INPUT unexpected (ident or '/' wanted)'
+Warning	1512	Incorrect XML value: 'parse error at line 1 pos 6: END-OF-INPUT unexpected (ident or '/' wanted)'
 select extractValue('<a>a</','/a');
 extractValue('<a>a</','/a')
 NULL
 Warnings:
-Warning	1504	Incorrect XML value: 'parse error at line 1 pos 7: END-OF-INPUT unexpected (ident wanted)'
+Warning	1512	Incorrect XML value: 'parse error at line 1 pos 7: END-OF-INPUT unexpected (ident wanted)'
 select extractValue('<a>a</a','/a');
 extractValue('<a>a</a','/a')
 NULL
 Warnings:
-Warning	1504	Incorrect XML value: 'parse error at line 1 pos 8: END-OF-INPUT unexpected ('>' wanted)'
+Warning	1512	Incorrect XML value: 'parse error at line 1 pos 8: END-OF-INPUT unexpected ('>' wanted)'
 select extractValue('<a>a</a></b>','/a');
 extractValue('<a>a</a></b>','/a')
 NULL
 Warnings:
-Warning	1504	Incorrect XML value: 'parse error at line 1 pos 12: '</b>' unexpected (END-OF-INPUT wanted)'
+Warning	1512	Incorrect XML value: 'parse error at line 1 pos 12: '</b>' unexpected (END-OF-INPUT wanted)'
 select extractValue('<a b=>a</a>','/a');
 extractValue('<a b=>a</a>','/a')
 NULL
 Warnings:
-Warning	1504	Incorrect XML value: 'parse error at line 1 pos 7: '>' unexpected (ident or string wanted)'
+Warning	1512	Incorrect XML value: 'parse error at line 1 pos 7: '>' unexpected (ident or string wanted)'
 select extractValue('<e>1</e>','position()');
 ERROR HY000: XPATH syntax error: ''
 select extractValue('<e>1</e>','last()');