Fix the V2 jamfile name so that it works on Windows as well.

[SVN r17544]

boost-build.jam

@@ -8,7 +8,7 @@ if --v2 in $(ARGV)
     }
     else
     {
-        JAMFILE = Jamfile.v2 ;
+        JAMFILE = [Jj]amfile.v2 ;
 	boost-build tools/build/new ;
     }	
 }