Add patches from upstream to fix crash bugs

- CVE-2017-6312: out-of-bounds read in ico (Closes: #856444)
- CVE-2017-6313: integer underflow in icns (Closes: #856445)
- CVE-2017-6314: infinite loop in tiff (Closes: #856448)

Thanks to Salvatore Bonaccorso for highlighting the relevant commits.