Add support for Optional parameter to build definitions

Build definitions can now specify Optional.  If Optional is not
specified the build definition will be followed by a default definition
for all outputs.

Change-Id: Iada83b2ef32bfb599b3cc580263f12bc002e1cdb
1 file changed
tree: eb2ed51a1014a3fe00ed98c87c00f538ac8e7597
  1. blueprint/
  2. Blueprints
  3. bootstrap.bash
  4. build.ninja.in