Remove CONFIG_{DE,EN}CODERS from the CMake build.

Use CONFIG_AV1_{DE,EN}CODER to control decoder and
encoder support inclusion instead.

BUG=aomedia:76,aomedia:508

Change-Id: Ib150ae382b301885589f30d9b6e98d3bfdd1afce
diff --git a/tools_common.c b/tools_common.c
index 3530210..d1115ac 100644
--- a/tools_common.c
+++ b/tools_common.c
@@ -128,12 +128,9 @@
   return shortread;
 }
 
-#if CONFIG_ENCODERS
-
-static const AvxInterface aom_encoders[] = {
 #if CONFIG_AV1_ENCODER
+static const AvxInterface aom_encoders[] = {
   { "av1", AV1_FOURCC, &aom_codec_av1_cx },
-#endif
 };
 
 int get_aom_encoder_count(void) {
@@ -152,15 +149,11 @@
 
   return NULL;
 }
+#endif  // CONFIG_AV1_ENCODER
 
-#endif  // CONFIG_ENCODERS
-
-#if CONFIG_DECODERS
-
-static const AvxInterface aom_decoders[] = {
 #if CONFIG_AV1_DECODER
+static const AvxInterface aom_decoders[] = {
   { "av1", AV1_FOURCC, &aom_codec_av1_dx },
-#endif
 };
 
 int get_aom_decoder_count(void) {
@@ -190,8 +183,7 @@
 
   return NULL;
 }
-
-#endif  // CONFIG_DECODERS
+#endif  // CONFIG_AV1_DECODER
 
 // TODO(dkovalev): move this function to aom_image.{c, h}, so it will be part
 // of aom_image_t support