Explicitly list out our source dirs

Afaik it was still faster due to not needing some kind of directory scan. Might be no longer true, but yeah nothing wrong with this just in case.

Author: chenglou

bsconfig.json

@@ -4,11 +4,10 @@
   "sources": [
     {
       "dir": "src",
-      "subdirs": true
+      "subdirs": ["intl", "typed-arrays"]
     },
     {
       "dir": "test",
-      "subdirs": true,
       "type": "dev"
     }
   ],