* gnu/packages/gtk.scm (cairo)[replacement]: New field.
(cairo/fixed): New variable.
(cairo-xcb)[source]: Use patch.
[replacement]: New field, set false.
* gnu/packages/pdf.scm (poppler)[inputs]: Custom cairo should be
replaced by a new custom patched cairo.
* gnu/packages/patches/cairo-CVE-2016-9082.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
