AddReserve had bogus prepare statement.

AddReserve had bogus prepare statement.

This patch was not fully tested because the actual behavior intended
by constraints 'o' and 'e' was apparently never implemented here.
But it had no chance of success as with:
    my $sth = $dbh->prepare("");

This uses the inteneded query, removes unneeded $sth->finish calls and
fixes *some* redeclaration of my $variables in the same scope, as
would be needed to run under warnings pragma.

Signed-off-by: Galen Charlton <galen.charlton@liblime.com>
Signed-off-by: Henri-Damien LAURENT <henridamien.laurent@biblibre.com>