Bug 36187: Corrected set data.patron_id in select_suggestor()

Bug 36187: Corrected set data.patron_id in select_suggestor()

To test:
1. Make a new suggestion in the staff interface and attempt to set the "Created by" patron to someone other than the logged in user.
2. Submit the suggestion.
3. select suggestedby from suggestions where suggestionid = X; ( Where X is the suggestionid )
4. The value is NULL
5. On suggestion/suggestion.pl the "Suggested by" column is blank.
6. APPLY PATCH
7. Try 1 - 3 again. This time the suggestedby should be correctly set.

Signed-off-by: Andrew Fuerste Henry <andrewfh@dubcolib.org>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit 607b80c5a601f54920a2b3b259896ac4e490e0ab)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>