Bug#56895 part 1 of 2: Backport of revid...

Bug#56895 part 1 of 2: Backport of revid holyfoot@mysql.com-20100823084827-js10vjuil88je35r from mysql-5.5.
The purpose is to make MTR logic for mysqlhotcopy the same in 5.1 as in 5.5, making it easier to maintain and fix bugs such as 56817.

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

@@ -2145,7 +2145,10 @@ sub environment_setup {
     mtr_pl_maybe_exists("$basedir/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