Fix PPC movrel issue in FFmpeg libs.

Fixes #9916

Cherry-picked from:
http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2d16394f972dca8cc5e5b5bf9ab0b343a6239b76

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: Gavin Hurlbut <ghurlbut@mythtv.org>
(cherry picked from commit 2ed7b53)

mythtv/external/FFmpeg/libavcodec/ppc/asm.S

@@ -67,7 +67,11 @@ X(\name):
 
 .macro movrel rd, sym
 #if CONFIG_PIC
-    lwz     \rd, \sym@got(r2)
+    bcl             20, 31, lab_pic_\@
+lab_pic_\@:
+    mflr    \rd
+    addis   \rd, \rd, (\sym - lab_pic_\@)@ha
+    addi    \rd, \rd, (\sym - lab_pic_\@)@l
 #else
     lis     \rd, \sym@ha
     la      \rd, \sym@l(\rd)