If running the mysql_upgrade test case with Valgrind, the resource

consumption (CPU) for upgrading a large log table can be intense.
Therefore, truncate the general_log table beforehand if running
mysql_upgrade test with Valgrind.

mysql-test/t/mysql_upgrade.test:
  Truncate log table if running with Valgrind.

mysql-test/t/mysql_upgrade.test

@@ -7,6 +7,26 @@
 select LENGTH("$MYSQL_UPGRADE")>0 as have_mysql_upgrade;
 --enable_query_log
 
+#
+# Hack:
+#
+# If running with Valgrind ($VALGRIND_TEST <> 0) then the resource
+# consumption (CPU) for upgrading a large log table will be intense.
+# Therefore, truncate the log table in advance and issue a statement
+# that should be logged.
+#
+if (`SELECT $VALGRIND_TEST`)
+{
+  --disable_query_log
+  --disable_result_log
+  --disable_abort_on_error
+  TRUNCATE TABLE mysql.general_log;
+  SELECT 1;
+  --enable_abort_on_error
+  --enable_result_log
+  --enable_query_log
+}
+
 #
 # Basic test that we can run mysql_upgrde and that it finds the
 # expected binaries it uses.