build: make linux/arm64 package

Fixes #3042

scripts/build.sh

@@ -14,7 +14,7 @@ DIR="$( cd -P "$( dirname "$SOURCE" )/.." && pwd )"
 cd "$DIR"
 
 # Determine the arch/os combos we're building for
-XC_ARCH=${XC_ARCH:-"386 amd64 arm"}
+XC_ARCH=${XC_ARCH:-"386 amd64 arm arm64"}
 XC_OS=${XC_OS:-"solaris darwin freebsd linux windows"}
 
 # Delete the old dir
@@ -34,7 +34,7 @@ echo "==> Building..."
 "`which gox`" \
     -os="${XC_OS}" \
     -arch="${XC_ARCH}" \
-    -osarch="!darwin/arm" \
+    -osarch="!darwin/arm !darwin/arm64" \
     -ldflags "${GOLDFLAGS}" \
     -output "pkg/{{.OS}}_{{.Arch}}/consul" \
     -tags="${GOTAGS}" \