nova: set invalid affinity space in thread constructor

Otherwise affinity space is set to 1x1 and in cpu_session_component.cc the cpu
session local affinity space defined by parent is not taken because
"Location::valid()" returns true.

Issue #1107
init: put ep for child in affinity space of child

Issue #1107
base: set default cpu affinity

Set cpu_session default affinity space already during
construction of the thread, so that main thread is placed in the cpu affinity
space as defined by the parent. Otherwise the main thread is placed potentially
outside the affinity space, typically on the first/boot CPU.

Fixes #1107