- Backported the 5.1 DBUG to 5.0.
- Avoid memory cleanup race on Windows client for CTRL-C


client/mysql.cc:
  Bug#26243 mysql command line crash after control-c
  - On Windows, the sigint handler shouldn't call mysql_end
  because the main thread will do so automatically.
  - Remove unnecessary signal call from the sigint handler.
  - Call my_end with proper value.
dbug/dbug.c:
  Bug#26243 mysql command line crash after control-c
  - Backported the 5.1 DBUG library. The old version uses a non-thread 
  safe global variable 'static struct state *stack'.
dbug/factorial.c:
  Bug#26243 mysql command line crash after control-c
  - Backported the 5.1 DBUG library. The old version uses a non-thread 
  safe global variable 'static struct state *stack'.
dbug/user.r:
  Bug#26243 mysql command line crash after control-c
  - Backported the 5.1 DBUG library. The old version uses a non-thread 
  safe global variable 'static struct state *stack'.
include/my_dbug.h:
  Bug#26243 mysql command line crash after control-c
  - Backported the 5.1 DBUG library. The old version uses a non-thread 
  safe global variable 'static struct state *stack'.
libmysql/libmysql.c:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
myisam/mi_open.c:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/ha_federated.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/ha_innodb.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/ha_myisammrg.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/item_cmpfunc.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/mysqld.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/net_serv.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/opt_range.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/set_var.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/slave.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/sql_cache.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
sql/sql_select.cc:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.
tests/mysql_client_test.c:
  Bug#26243 mysql command line crash after control-c
  - Update for new DBUG library.