Parallelize Blueprints file parsing

Parse multiple Blueprints files simultaneously by using a goroutine
to read the file, call the module factory, parse the properties,
and look for subdirectories.  Requires module factories to be
reentrant, but otherwise does not change any build logic semantics.

Change-Id: Ia07579917a2b6fd064cedbfff655c23d706da718
3 files changed
tree: c5c77dbf4c486739e712839a5899242708469d52
  1. blueprint/
  2. Blueprints
  3. bootstrap.bash
  4. build.ninja.in