Add a Makefile rule for the little-endian G.726 decoder.

Fixes compilation with --disable-everything --enable-decoder=adpcm_g726le

libavcodec/Makefile

@@ -598,6 +598,7 @@ OBJS-$(CONFIG_ADPCM_G722_DECODER)         += g722.o g722dec.o
 OBJS-$(CONFIG_ADPCM_G722_ENCODER)         += g722.o g722enc.o
 OBJS-$(CONFIG_ADPCM_G726_DECODER)         += g726.o
 OBJS-$(CONFIG_ADPCM_G726_ENCODER)         += g726.o
+OBJS-$(CONFIG_ADPCM_G726LE_DECODER)       += g726.o
 OBJS-$(CONFIG_ADPCM_IMA_AMV_DECODER)      += adpcm.o adpcm_data.o
 OBJS-$(CONFIG_ADPCM_IMA_APC_DECODER)      += adpcm.o adpcm_data.o
 OBJS-$(CONFIG_ADPCM_IMA_DK3_DECODER)      += adpcm.o adpcm_data.o