xvidcore: Update to 1.3.6

Changes since 1.3.6:

* Fix for a regression in initializing the Inter matrix with MPEG
  Quantization

Changes since 1.3.5:

* Fix for various, long-standing and potentially critical security
  vulnerabilities in the decoder (credit to OSS-Fuzz)
* Always use .text sections in nasm code for macho target

Changes since 1.3.4:

* AmigaOS build patch by Fredrik Wikstrom
* Support for applevel multithreading mode also for AVI output in
  xvid_encraw
* Set interlacing flag in decoder correctly

(nia)