Fix to be able to run

mysql-test-run --manager --valgrind
(without this fix, the manager fails to start mysqld and the tests hang).


mysql-test/mysql-test-run.sh:
  When running with --manager: the MySQL manager wants the complete path of the
  executable (it uses execv(), not execvp(), so does not search in the $PATH,
  so telling him to start 'valgrind' is not enough, it wants '/usr/bin/valgrind'
  or so).
  So this is a fix to be able to
  mysql-test-run --manager --valgrind
  Plus a warning (previously, if valgrind was not installed, tests silently
  hanged when run with --valgrind).

mysql-test/mysql-test-run.sh

@@ -336,7 +336,13 @@ while test $# -gt 0; do
       EXTRA_SLAVE_MYSQLD_OPT="$EXTRA_SLAVE_MYSQLD_OPT --gdb"
       ;;
     --valgrind)
-      VALGRIND="valgrind --alignment=8 --leak-check=yes --num-callers=16"
+      VALGRIND=`which valgrind` # this will print an error if not found
+      # Give good warning to the user and stop
+      if [ -z "$VALGRIND" ] ; then
+        $ECHO "You need to have the 'valgrind' program in your PATH to run mysql-test-run with option --valgrind. Valgrind's home page is http://developer.kde.org/~sewardj ."
+        exit 1
+      fi
+      VALGRIND="$VALGRIND --alignment=8 --leak-check=yes --num-callers=16"
       EXTRA_MASTER_MYSQLD_OPT="$EXTRA_MASTER_MYSQLD_OPT --skip-safemalloc --skip-bdb"
       EXTRA_SLAVE_MYSQLD_OPT="$EXTRA_SLAVE_MYSQLD_OPT --skip-safemalloc --skip-bdb"
       SLEEP_TIME_AFTER_RESTART=10