avcodec/arm/videodsp_armv5te: Fix linking failure with "g++ -shared…

avcodec/arm/videodsp_armv5te: Fix linking failure with "g++ -shared -D__STDC_CONSTANT_MACROS -o test.so ... libavcodec.a"

Tested-by: Andreas Haupt
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit cab63025)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/arm/videodsp_armv5te.S

@@ -23,9 +23,10 @@
 #include "libavutil/arm/asm.S"
 
 function ff_prefetch_arm, export=1
+1:
         subs            r2,  r2,  #1
         pld             [r0]
         add             r0,  r0,  r1
-        bne             X(ff_prefetch_arm)
+        bne             1b
         bx              lr
 endfunc