tests: Introduced new config option to add extra stack size for tests.

This option is added in order to support Xtensa, which needs more stack than
other architecture. This allows having a centralized way to change stack
requirements for all tests.
This extra stack size is eaqual to 0 for most architectures, except Xtensa
which requires additional 768 bytes for each stack.

Change-Id: Ie5dcae1dfd29018d36ef35dae22dc4c1a2ecdc14
Signed-off-by: Mazen NEIFER <mazen@nestwave.com>
16 files changed