swscale: split scale.asm.

scale.asm keeps horizontal scaling functions, whereas output.asm gets
the vertical scaling/output functions.

libswscale/Makefile

@@ -17,7 +17,8 @@ OBJS-$(HAVE_MMX)           +=  x86/rgb2rgb.o            \
                                x86/swscale_mmx.o        \
                                x86/yuv2rgb_mmx.o
 OBJS-$(HAVE_VIS)           +=  sparc/yuv2rgb_vis.o
-MMX-OBJS-$(HAVE_YASM)      +=  x86/scale.o
+MMX-OBJS-$(HAVE_YASM)      +=  x86/output.o             \
+                               x86/scale.o
 
 TESTPROGS = colorspace swscale