Skip projects when property refinement for them fails.

Skip main targets when no alternative can be build.
Issue error when 'construct' for alternative fails.


[SVN r15676]

tools/build

@@ -1 +1 @@
-Subproject commit da0376118c194e119cfcb96f4665acbe1263e8ff
+Subproject commit 9fa663224f42bf813fe260e8c660595eae755598