It should only worry about its parent directory, not its grandparent.
This makes it possible to bind mount just daemon/contrib in a
container, to run 'make fetch' for example.

* contrib/bootstrap: Adjust relative paths.
* contrib/src/main.mak: Express using the CURDIR variable.
(PATH): Express using the TOPSRC variable.
(pkg_static): Express using the SRC environment variable.

Change-Id: I02cba2249e4971d76ef0af0fa00f4b1af61c5aff