Revert "Fix building libopencore_amrnb decoder without libopencore_amrnb encoder"

Reverting "Fix" because it disables amrwb decoder.

This reverts commit e11020a145.

libavcodec/Makefile

@@ -665,6 +665,7 @@ OBJS-$(CONFIG_LIBOPENCORE_AMRNB_DECODER)  += libopencore-amr.o \
                                              audio_frame_queue.o
 OBJS-$(CONFIG_LIBOPENCORE_AMRNB_ENCODER)  += libopencore-amr.o \
                                              audio_frame_queue.o
+OBJS-$(CONFIG_LIBOPENCORE_AMRWB_DECODER)  += libopencore-amr.o
 OBJS-$(CONFIG_LIBOPENJPEG_DECODER)        += libopenjpegdec.o
 OBJS-$(CONFIG_LIBOPENJPEG_ENCODER)        += libopenjpegenc.o
 OBJS-$(CONFIG_LIBSCHROEDINGER_DECODER)    += libschroedingerdec.o \