* Seal away private thread and kernel definitions and declarations
into the internal headers in order to better hide internal structure.
* Add a thread-common.c file that keeps shared functions together.
List functions aren't messed with since that's about to be changed to
different ones.
* It is necessary to modify some ARM/PP stuff since GCC was complaining
about constant pool distance and I would rather not force dump it. Just
bl the cache calls in the startup and exit code and let it use veneers
if it must.
* Clean up redundant #includes in relevant areas and reorganize them.
* Expunge useless and dangerous stuff like remove_thread().
Change-Id: I6e22932fad61a9fac30fd1363c071074ee7ab382
