lavfi/Makefile: Don't compile lavfutils.c and lswsutils.c if they are not needed

They are only needed by removelogo.
This fixes a link failure in shared builds when compiling with
removelogo disabled but Lavf/SwS enabled
Signed-off-by: James Almer <jamrial@gmail.com>
Reviewed-by: Stefano Sabatini <stefasab@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavfilter/Makefile

@@ -49,8 +49,6 @@ OBJS = allfilters.o                                                     \
 
 
 OBJS-$(CONFIG_AVCODEC)                       += avcodec.o
-OBJS-$(CONFIG_AVFORMAT)                      += lavfutils.o
-OBJS-$(CONFIG_SWSCALE)                       += lswsutils.o
 
 OBJS-$(CONFIG_ACONVERT_FILTER)               += af_aconvert.o
 OBJS-$(CONFIG_ADELAY_FILTER)                 += af_adelay.o