Bug 17234: Add constraint_exists and column_exists to updatedatabase.pl

Bug 17234: Add constraint_exists and column_exists to updatedatabase.pl

These 2 subroutines will help us deal with the absense of ALTER IGNORE
TABLE

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit c08922180e83b0222dc3d54a292aaf49cc15000a)
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
(cherry picked from commit 70fe225bea608b61b40f237a13195eb028da4231)
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>