gnucash maint: Fix a couple of warnings introduced by commit 01420adb9989f49a

[Geert Janssens]

Updated	 via  https://github.com/Gnucash/gnucash/commit/80dbb994 (commit)
	from  https://github.com/Gnucash/gnucash/commit/87f94abc (commit)



commit 80dbb9940b77df40fc1854d0593ecf5f716597c9
Author: Geert Janssens <geert at kobaltwit.be>
Date:   Tue Apr 17 19:45:39 2018 +0200

    Fix a couple of warnings introduced by commit 01420adb9989f49a
    
    In addition make the code really use an inner join if no additional conditions are set
    which gives better performance on at least postgresql



Summary of changes:
 libgnucash/backend/sql/gnc-transaction-sql.cpp | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)