Support use of unversioned and unrooted initialization of the toolset. In which case an attempt is made to find the intended root from a path search. Additionaly fixed the precense of -L"" when an unrooted initialization happens.

[SVN r18882]

tools/build

@@ -1 +1 @@
-Subproject commit 83613575f46261e6e34920f18fa9195dca08127b
+Subproject commit bf328b82e93f7327dade49b0e301bda84252babb