url_helpers: Fix snprintf size problems
url_helpers: Fix snprintf size problems

In commits:

f4e5ae8a 'url_helpers: Use snprintf instead of strcpy in do_edit_user'
60da59bb 'url_helpers: Use snprintf instead of strcpy in do_update_user'

We used sizeof(hash) for the size argument to snprintf. However, hash is
malloc'd memory and thus sizeof(hash) is just sizeof a pointer.

Use strlen(row[0]) + 1 instead, which is what's been allocated for hash.

Signed-off-by: Andrew Clayton <02e0a999c50b1f88df7a8f5a04e1b76b35ea6a88@opentechlabs.co.uk>

ac000/receiptomatic