fcl-db: mssql: if stored procedure raises error with severity > 10 then db-library calls error handler, which sets DBErrorNo and DBErrorStr. So check them after execution of SQL and raise also error if they are set. +Cancel any pending results or other commands in batch to allow ROLLBACK.

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@28944 3ad0048d-3df7-0310-abae-a5850022a9f2