Bug 16886: Make the 'Upload patron images' tool plack safe

Bug 16886: Make the 'Upload patron images' tool plack safe

Some vars are accessed from subroutine, but defined with my.
It causes at least the 2 followings errors:
Variable "$filetype" is not available at
/home/koha/src/tools/picture-upload.pl line 240.
Variable "$uploadfilename" is not available at
/home/koha/src/tools/picture-upload.pl line 241.

To avoid that, they are now declared with our.

Test plan:
Upload image for a patron and confirm that you get a "Result" table and
the errors do not longer appear in the logs.

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Katrin Fischer  <katrin.fischer@bsz-bw.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>