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.