test: ipc: reorganize suite definitions, fix mutate_tid()

The latter wouldn't always produce a global ID. It now does by always setting
bit 1.
fix syscall stub for SpaceControl

GCC would change [redir] to a %esp index, causing a bug inside the push/pop of
%ebp. As solution, __L4_SAVE_REGS was moved two instructions down and the code
was marked non-__pic__.
ipc: fix local sender matching

The waiting IPC only needs to look like it's local. Conversely, if it looks
global it's not received even when the propagator is a local thread.