Look for mysqlslap from 5.1, it's also available on windows

mysql-test/mysql-test-run.pl

@@ -1307,6 +1307,10 @@ sub executable_setup () {
   $exe_mysqlbinlog=    mtr_exe_exists("$path_client_bindir/mysqlbinlog");
   $exe_mysqladmin=     mtr_exe_exists("$path_client_bindir/mysqladmin");
   $exe_mysql=          mtr_exe_exists("$path_client_bindir/mysql");
+  if ( $mysql_version_id >= 50100 )
+  {
+    $exe_mysqlslap=      mtr_exe_exists("$path_client_bindir/mysqlslap");
+  }
 
   # Look for mysql_fix_system_table script
   $exe_mysql_fix_system_tables=
@@ -1540,8 +1544,6 @@ sub environment_setup () {
   # ----------------------------------------------------
   # Setup env so childs can execute mysqlslap
   # ----------------------------------------------------
-  unless ( $glob_win32 )
-  {
   my $cmdline_mysqlslap=
     "$exe_mysqlslap -uroot " .
     "--port=$master->[0]->{'port'} " .
@@ -1554,7 +1556,6 @@ sub environment_setup () {
       " --debug=d:t:A,$path_vardir_trace/log/mysqlslap.trace";
   }
   $ENV{'MYSQL_SLAP'}= $cmdline_mysqlslap;
-  }
 
   # ----------------------------------------------------
   # Setup env so childs can execute mysqlimport