it returns misleading 'table is full'

Innodb returns a misleading error message "table is full" 
when the number of active concurrent transactions is greater
than 1024.

Fixed by adding errorcode "ER_TOO_MANY_CONCURRENT_TRXS" to the
error codes. Innodb should return HA_TOO_MANY_CONCURRENT_TRXS
to mysql which is then mapped to ER_TOO_MANY_CONCURRENT_TRXS


Note: testcase is not written as this was reproducible only by
      changing innodb code.

extra/perror.c:
  Add error number and message for HA_ERR_TOO_MANY_CONCURRENT_TRXS
include/my_base.h:
  Add error number and message for HA_ERR_TOO_MANY_CONCURRENT_TRXS
sql/ha_innodb.cc:
  Return HA_ERR_TOO_MANY_CONCURRENT_TRXS to mysql server
sql/handler.cc:
  Add error number and message for HA_ERR_TOO_MANY_CONCURRENT_TRXS
sql/share/errmsg.txt:
  Add error message for ER_TOO_MANY_CONCURRENT_TRXS