Expand subfeatures in the conditinal properties found in project requirements.

This means that <toolset>gcc-3.3:<define>FOOBAR in project properties now
works.


[SVN r24778]

tools/build

@@ -1 +1 @@
-Subproject commit 687ff601785eac150942233d137ba8aa1d4f294d
+Subproject commit 79c0ddb5d7e304b80dd98b0141672bc7ede99131