configure: Remove a stray msmpeg4v1 encoder declaration

No such encoder exists currently.

Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -1578,7 +1578,6 @@ mpeg2video_encoder_select="aandcttables mpegvideoenc"
 mpeg4_decoder_select="h263_decoder mpeg4video_parser"
 mpeg4_encoder_select="h263_encoder"
 msmpeg4v1_decoder_select="h263_decoder"
-msmpeg4v1_encoder_select="h263_encoder"
 msmpeg4v2_decoder_select="h263_decoder"
 msmpeg4v2_encoder_select="h263_encoder"
 msmpeg4v3_decoder_select="h263_decoder"