This patch alleviates the need for a Native_capability::Dst at the API
level. The former use case of this type as argument to
Deprecated_env::reinit uses the opaque Native_capability::Raw type
instead. The 'Raw' type contains the portion of the capability that is
transferred as-is when delegating the capability (i.e., when installing
the parent capability into a new component, or when installing a new
parent capability into a new forked Noux process). This information can
be retrieved via the new Native_capability::raw method.
Furthermore, this patch moves the functions for retriving the parent
capability to base/internal/parent_cap.h, which is meant to be
implemented in platform-specific ways. It replaces the former set of
startup/internal/_main_parent_cap.h headers.
Issue #1993
To circumvent compilation errors with the older L4Android Linux kernel
version, the ballooning driver is included in the more recent L4Linux
kernel only. Moreover, to be able to maintain L4Android / L4Linux in a more
convenient way, e.g. to apply patches valid for both versions, we use
the same git clone that is used for L4Linux instead of using the upstream
L4Android version by applying patches.
Fixes#1390
