Modify xaccAccountChildrenEqual to not depend upon the order

A SQL backend can't be expected to always return children in the same order.

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23173 57a11ea4-9604-0410-9ed3-97b8803252fd
Bug 674862 - 2038 bug in libdbi

Retrieve the numerical value directly from the dbi_result and use
it to create the Timespec or GDate.
BP

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash/trunk@23174 57a11ea4-9604-0410-9ed3-97b8803252fd