Changed defaults when running mysql-test-run to ensure that

Pushbuild servers are not overloaded and test cases crash
due to overload of memory and disk.

mysql-test/include/default_mysqld.cnf

@@ -14,6 +14,11 @@ sort_buffer=                256K
 max_heap_table_size=        1M
 
 loose-innodb_data_file_path=      ibdata1:10M:autoextend
+loose-innodb_buffer_pool_size=    64M
+loose-innodb_write_io_threads=    2
+loose-innodb_read_io_threads=     2
+loose-innodb_log_buffer_size=     4M
+loose-innodb_log_file_size=       32M
 
 slave-net-timeout=120