Fix dependencies for the ra_144 encoder

Patch by Francesco Lavra, francescolavra at interfree dot it

Originally committed as revision 23748 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1271,7 +1271,7 @@ png_decoder_select="zlib"
 png_encoder_select="zlib"
 qcelp_decoder_select="lsp"
 qdm2_decoder_select="mdct rdft"
-real_144_encoder_select="lpc"
+ra_144_encoder_select="lpc"
 rv10_decoder_select="h263_decoder"
 rv10_encoder_select="h263_encoder"
 rv20_decoder_select="h263_decoder"