Do not build node with sync by default

scripts/test.sh

@@ -186,10 +186,11 @@ case "$TARGET" in
     download_server
     start_server
     npm_tests_cmd="npm run test"
+    npm install --build-from-source --realm_enable_sync
   else
     npm_tests_cmd="npm run test-nosync"
+    npm install --build-from-source
   fi
-  npm install --build-from-source
 
   # Change to a temp directory.
   cd "$(mktemp -q -d -t realm.node.XXXXXX)"

src/node/gyp/realm.gyp

@@ -5,7 +5,7 @@
   "conditions": [
     ["OS=='mac'", {
       "variables": {
-        "realm_enable_sync%": "1"
+        "realm_enable_sync%": "0"
       }
     }, {
       "variables": {