Trivial backport of 6540fe04a3f9a11ba7084a49b3ee5fa2fc5b32ab

VP8E_UPD_ENTROPY, VP8E_UPD_REFERENCE, VP8E_USE_REFERENCE were removed
from libvpx and the remaining values were never used here

diff -Nur ffmpeg-0.10.9.orig/libavcodec/libvpxenc.c ffmpeg-0.10.9/libavcodec/libvpxenc.c
--- ffmpeg-0.10.9.orig/libavcodec/libvpxenc.c	2013-09-26 20:10:34.000000000 -0500
+++ ffmpeg-0.10.9/libavcodec/libvpxenc.c	2016-01-09 18:23:21.957215252 -0600
@@ -78,19 +78,11 @@
 
 /** String mappings for enum vp8e_enc_control_id */
 static const char *ctlidstr[] = {
-    [VP8E_UPD_ENTROPY]           = "VP8E_UPD_ENTROPY",
-    [VP8E_UPD_REFERENCE]         = "VP8E_UPD_REFERENCE",
-    [VP8E_USE_REFERENCE]         = "VP8E_USE_REFERENCE",
-    [VP8E_SET_ROI_MAP]           = "VP8E_SET_ROI_MAP",
-    [VP8E_SET_ACTIVEMAP]         = "VP8E_SET_ACTIVEMAP",
-    [VP8E_SET_SCALEMODE]         = "VP8E_SET_SCALEMODE",
     [VP8E_SET_CPUUSED]           = "VP8E_SET_CPUUSED",
     [VP8E_SET_ENABLEAUTOALTREF]  = "VP8E_SET_ENABLEAUTOALTREF",
     [VP8E_SET_NOISE_SENSITIVITY] = "VP8E_SET_NOISE_SENSITIVITY",
-    [VP8E_SET_SHARPNESS]         = "VP8E_SET_SHARPNESS",
     [VP8E_SET_STATIC_THRESHOLD]  = "VP8E_SET_STATIC_THRESHOLD",
     [VP8E_SET_TOKEN_PARTITIONS]  = "VP8E_SET_TOKEN_PARTITIONS",
-    [VP8E_GET_LAST_QUANTIZER]    = "VP8E_GET_LAST_QUANTIZER",
     [VP8E_SET_ARNR_MAXFRAMES]    = "VP8E_SET_ARNR_MAXFRAMES",
     [VP8E_SET_ARNR_STRENGTH]     = "VP8E_SET_ARNR_STRENGTH",
     [VP8E_SET_ARNR_TYPE]         = "VP8E_SET_ARNR_TYPE",