This patch reverts a change introduced by Bug 6951, which incorrectly
set thd->abort_on_warning for stored procedures.

As per internal discussions about the SQL_MODE=TRADITIONAL,
the correct behavior is to *not* abort on warnings even inside an INSERT/UPDATE
trigger.

Tests for Stored Procedures, Stored Functions, Triggers involving SQL_MODE
have been included or revised, to reflect the intended behavior.

(reposting approved patch, to work around source control issues, no review needed)


mysql-test/include/sp-vars.inc:
  Tests for SQL_MODE='TRADITIONAL'
mysql-test/r/sp-vars.result:
  Tests for SQL_MODE='TRADITIONAL'
mysql-test/r/sp.result:
  Tests for SQL_MODE='TRADITIONAL'
mysql-test/r/trigger.result:
  Tests for SQL_MODE='TRADITIONAL'
mysql-test/t/sp-vars.test:
  Tests for SQL_MODE='TRADITIONAL'
mysql-test/t/sp.test:
  Tests for SQL_MODE='TRADITIONAL'
mysql-test/t/trigger.test:
  Tests for SQL_MODE='TRADITIONAL'
sql/sp_head.cc:
  For SQL_MODE='TRADITIONAL',
  thd->abort_on_warning should be set only when assigning a *column*