Bug 37382: Report download is empty except for headers if .tab format is selected

Bug 37382: Report download is empty except for headers if .tab format is selected

When exporting a report in tab delimited format, the downloaded file
    would have the header rows but no data results.
Also, misc files are created on the server file system in koha/reports
    with data that should have been in the .tab file.
This patch fixes both of these issues.

To test:
1. Login to staff client
2. Go to Reports and create a report from SQL - sample report
    SELECT i.barcode, b.title, b.biblionumber, i.itemnumber
	FROM items i
	LEFT JOIN biblio b on i.biblionumber = b.biblionumber
	WHERE i.itemnumber < 50
3. Run the report
4. Click 'Download'->'Tab separated text'
5. Download file
6. Open file in a text editor or favorite spreadsheet app
    File will have headers rows, but no other item data
6a. If able, check the server filesystem in koha/reports
	There may be files there related to report data. Remove.
7. Apply Patch
8. Repeat steps 3-6,
    File will now have the table data, hooray!
8a. If able, check the server filesystem in koha/reports
	No new files should be created.

Signed-off-by: Laura ONeil <laura@bywatersolutions.com>
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>