Remove x86 compiler warning caused by PPC cleanup

The way that CPU flags are handled in this filter needs rework.  There is no
sane reason that the MMX-specific labels should be visible in PPC, and vice
versa.  Just saving a few #if / #endif for prettiness doesn't make up for the
mess it made of the .o files.

mythtv/filters/linearblend/filter_linearblend.c

@@ -32,9 +32,12 @@ typedef struct LBFilter
 void linearBlend(unsigned char *src, int stride);
 void linearBlendMMX(unsigned char *src, int stride);
 void linearBlend3DNow(unsigned char *src, int stride);
-inline void linearBlendAltivec(unsigned char *src, int stride);
 int linearBlendFilterAltivec(VideoFilter *f, VideoFrame *frame, int field);
 
+#if HAVE_ALTIVEC
+inline void linearBlendAltivec(unsigned char *src, int stride);
+#endif
+
 #ifdef MMX
 
 void linearBlendMMX(unsigned char *src, int stride)