Use caching inside path.pwd. The PWD rule on windows calls the

short_path_to_long_path function which takes a lot of time, and clearly
current directory of bjam will never change as it's running.


[SVN r31138]

tools/build

@@ -1 +1 @@
-Subproject commit 669c8a0dbfb5fd6f908213fe63f43c9f0b1cc7a4
+Subproject commit 7af049ac8f18f5a5e63db1b5d9bb1b7e882de342