Add a PreGenerateBuildActions pass

Call PreGenerateBuildActions on each module that implments it after
resolving dependencies but before calling GenerateBuildActions on
any module.  This allows the build logic to propagate top-down
information, for example what variants of a library need to be
compiled for the binaries it is used in.

Change-Id: I2737504fa9d1a2b42ef747497de32c1c5129233d
2 files changed
tree: a7872a9681e511fa52b5af6edd6d8181b3500df8
  1. blueprint/
  2. Blueprints
  3. bootstrap.bash
  4. build.ninja.in