This patch moves details about the stack allocation and organization
the base-internal headers. Thereby, I replaced the notion of "thread
contexts" by "stacks" as this term is much more intuitive. The fact that
we place thread-specific information at the bottom of the stack is not
worth introducing new terminology.
Issue #1832
Former Native_config::context_area_virtual_base() was used to identify
the main, which is not desired as the Native_config is rather low-level
(almost private to the base libs). The commit uses a library constructor
to retrieve the main-thread Thread_base pointer, which can be used later
to distinguish main and other threads.
The pthread object for the main thread initializes its 'Thread_base' base
class part with a reference to the 'Thread_base' object of the Genode main
thread. Therefore the pthread object for the main thread should never be
destroyed, as this would also destroy the Genode 'Thread_base' object.
Fixes#1760
Defer destruction of threads which tries to self-destruct. Check an perform
cleanup of such threads during pthread_cancel and pthread_create.
Issue #1687
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
