Fix auto-link to look at the right variable.

Make boost-build.jam point at the v2 Boost.


[SVN r36318]

libs/python

@@ -1 +1 @@
-Subproject commit 8fe9d41b5879bcbf430a187dcfb4f544d122cf1d
+Subproject commit 0c4ebef57957eaba719f58b0fd239e18626d996f