(ok'd by CTO to fix it in 4.0).
Fix to make mysql-test-run work with all Valgrind versions.


mysql-test/mysql-test-run.sh:
  fixing mysql-test-run.sh so that it works indifferently with Valgrind 1.x, 2.x
  (versions <= 2.0.0 refuse --tool option; versions >=2.1.2 require it; 2.1.0 accepts it).
  I hope the shell code is portable enough; anyway Valgrind only runs on Linux...
  I tested it with 2.0.0, 2.1.0, 2.1.2.
mysql-test/r/truncate.result:
  result update
mysql-test/t/truncate.test:
  testing if TRUNCATE resets autoinc counter for temp tables (BUG#5033); testing difference with DELETE FROM.
sql/sql_delete.cc:
  in mysql_truncate(), always reset the autoinc counter, as manual says (even if it's a temp table, which was BUG#5033).