Fix a problem with 'use-project' which refers to child project. Thanks

to Austin Bingham for the bug report.

* new/project.jam
  (load): Don't mark project as loaded here.
  (load-jamfile): Mark it as loaded here.


[SVN r20439]

tools/build

@@ -1 +1 @@
-Subproject commit 75046002a2219f041c4c4be6e5fb42298846b1f5
+Subproject commit 2eb6750dbd62d7ccf92e26f207793e8bc8cc5151