avfilter/vf_colorbalance:: Fix for framecrc bitexact for 32bit and 64bit system

Signed-off-by: Limin Wang <lance.lmwang@gmail.com>

libavfilter/vf_colorbalance.c

@@ -111,7 +111,7 @@ static float get_component(float v, float l,
     v += m;
     v += h;
 
-    return av_clipf(v, 0, 1);
+    return av_clipf(v + 0.5f, 0, 1);
 }
 
 static float hfun(float n, float h, float s, float l)