build: Make the E-AC-3 encoder select the AC-3 encoder

The E-AC-3 encoder depends on almost all of the code of the AC-3
encoder, so it makes no sense to enable one without the other.

configure

@@ -1360,7 +1360,7 @@ dca_decoder_select="mdct"
 dnxhd_encoder_select="aandcttables mpegvideoenc"
 dxa_decoder_select="zlib"
 eac3_decoder_select="ac3_decoder"
-eac3_encoder_select="mdct ac3dsp"
+eac3_encoder_select="ac3_encoder"
 eamad_decoder_select="aandcttables error_resilience"
 eatgq_decoder_select="aandcttables"
 eatqi_decoder_select="aandcttables error_resilience mpegvideo"

libavcodec/Makefile

@@ -144,8 +144,7 @@ OBJS-$(CONFIG_DVVIDEO_ENCODER)         += dv.o dvdata.o dv_profile.o
 OBJS-$(CONFIG_DXA_DECODER)             += dxa.o
 OBJS-$(CONFIG_DXTORY_DECODER)          += dxtory.o
 OBJS-$(CONFIG_EAC3_DECODER)            += eac3dec.o eac3_data.o
-OBJS-$(CONFIG_EAC3_ENCODER)            += eac3enc.o ac3enc.o ac3enc_float.o \
-                                          ac3tab.o ac3.o kbdwin.o eac3_data.o
+OBJS-$(CONFIG_EAC3_ENCODER)            += eac3enc.o eac3_data.o
 OBJS-$(CONFIG_EACMV_DECODER)           += eacmv.o
 OBJS-$(CONFIG_EAMAD_DECODER)           += eamad.o eaidct.o mpeg12.o \
                                           mpeg12data.o