mysql-test-run.pl : Fix the search path for "ndb_mgmd" and "ndbd". bug#21721

mysql-test/mysql-test-run.pl:
  In 5.1 packages, the binaries "ndbd" and "ndb_mgmd" are in subdirectory "bin", not in "libexec".
  Use the search function "mtr_exe_exists()", in case there might be exceptions.

mysql-test/mysql-test-run.pl

@@ -1299,8 +1299,10 @@ sub executable_setup () {
     $path_ndb_tools_dir=  "$glob_basedir/bin";
     $exe_ndb_mgm=         "$glob_basedir/bin/ndb_mgm";
     $exe_ndb_waiter=      "$glob_basedir/bin/ndb_waiter";
-    $exe_ndbd=            "$glob_basedir/libexec/ndbd";
-    $exe_ndb_mgmd=        "$glob_basedir/libexec/ndb_mgmd";
+    $exe_ndbd=            mtr_exe_exists("$glob_basedir/libexec/ndbd",
+                                         "$glob_basedir/bin/ndbd");
+    $exe_ndb_mgmd=        mtr_exe_exists("$glob_basedir/libexec/ndb_mgmd",
+                                         "$glob_basedir/bin/ndb_mgmd");
   }
 
   $exe_master_mysqld= $exe_master_mysqld || $exe_mysqld;