Build OSX ds_ctcdecoder in separate task

taskcluster/darwin-amd64-ctc-opt.yml

@@ -0,0 +1,14 @@
+build:
+  template_file: darwin-opt-base.tyml
+  allowed:
+    - "pull_request.opened"
+    - "pull_request.synchronize"
+    - "pull_request.reopened"
+  tensorflow: "https://index.taskcluster.net/v1/task/project.deepspeech.tensorflow.pip.r1.12.bea86c1e884730cf7f8615eb24d31872c198c766.osx/artifacts/public/home.tar.xz"
+  maxRunTime: 14400
+  scripts:
+    build: 'taskcluster/decoder-build.sh'
+    package: 'taskcluster/decoder-package.sh'
+  metadata:
+    name: "DeepSpeech CTC Decoder OSX AMD64 CPU"
+    description: "Building DeepSpeech CTC Decoder for OSX AMD64, CPU only, optimized version"

taskcluster/decoder-build.sh

@@ -4,6 +4,8 @@ set -xe
 
 source $(dirname "$0")/../tc-tests-utils.sh
 
+source ${DS_ROOT_TASK}/DeepSpeech/tf/tc-vars.sh
+
 export SYSTEM_TARGET=host
 
 do_deepspeech_decoder_build

taskcluster/host-build.sh

@@ -19,11 +19,6 @@ do_bazel_build
 
 do_deepspeech_binary_build
 
-# Decoder packages for Linux are built a separate task
-if [ "${OS}" = "Darwin" ]; then
-    do_deepspeech_decoder_build
-fi
-
 do_deepspeech_python_build
 
 do_deepspeech_nodejs_build