mysqlhotcopy tests fixed.

The include/mysqlhotcopy.inc had an error in the 'if' condition, so it failed
if the mysqlhotcopy tool was found.

per-file comments:
  mysql-test/include/mysqlhotcopy.inc
        test should proceed exactly if the mysqlhotcopy was set.
  mysql-test/mysql-test-run.pl
        don't set the MYSQL_HOTCOPY variable if no mysqlhotcopy was found.

mysql-test/include/mysqlhotcopy.inc

@@ -5,7 +5,7 @@
 --source include/not_windows.inc
 --source include/not_embedded.inc
 
-if ($MYSQLHOTCOPY)
+if (!$MYSQLHOTCOPY)
 {
   die due to missing mysqlhotcopy tool;
 }

mysql-test/mysql-test-run.pl

@@ -2158,7 +2158,10 @@ sub environment_setup {
     mtr_pl_maybe_exists("$bindir/scripts/mysqlhotcopy");
   # Since mysqltest interprets the real path as "false" in an if,
   # use 1 ("true") to indicate "not exists" so it can be tested for
-  $ENV{'MYSQLHOTCOPY'}= $mysqlhotcopy || 1;
+  if ($mysqlhotcopy)
+  {
+    $ENV{'MYSQLHOTCOPY'}= $mysqlhotcopy;
+  }
 
   # ----------------------------------------------------
   # perror