fix fulltext_plugin.test on windows

mysql-test/t/fulltext_plugin.test

@@ -3,7 +3,8 @@
 #
 # BUG#39746 - Debug flag breaks struct definition (server crash)
 #
-INSTALL PLUGIN simple_parser SONAME 'mypluglib.so';
+--replace_result .dll .so
+eval INSTALL PLUGIN simple_parser SONAME '$MYPLUGLIB_SO';
 CREATE TABLE t1(a TEXT, b TEXT, FULLTEXT(a) WITH PARSER simple_parser);
 ALTER TABLE t1 ADD FULLTEXT(b) WITH PARSER simple_parser;
 DROP TABLE t1;