Log message:
Pullup ticket #6325 - requested by he
multimedia/ffmpeg4: PowerPC build fix

Revisions pulled up:
- multimedia/ffmpeg4/hacks.mk                                   1.1

---
   Module Name:	pkgsrc
   Committed By:	he
   Date:		Mon Sep 14 20:43:36 UTC 2020

   Added Files:
   	pkgsrc/multimedia/ffmpeg4: hacks.mk

   Log message:
   Use -mvsx compiler flag on powerpc so that the appropriate section
   of the compiler's <altivec.h> header is exposed, so that this builds.