ext: Update NoMali to external rev f08e0a5

Update NoMali from external revision 9adf9d6 to f08e0a5 and bring in
the following changes:

f08e0a5 Add support for tracking address space state
f11099e Fix job slot register handling when running new jobs
b28c98e api: Add a reset callback
29ac4c3 tests: Update gitignore to cover all future test cases
1c6b893 Propagate reset calls to all job slots
8f8ec15 Remove redundant reg vector in MMU
85d90d2 tests: Fix incorrect extern declaration

scons: Enable -Wextra by default

Make best use of the compiler, and enable -Wextra as well as
-Wall. There are a few issues that had to be resolved, but they are
all trivial.

ext: Add the NoMali GPU no-simulation library

Add revision 9adf9d6e2d889a483a92136c96eb8a434d360561 of NoMali-model
from https://github.com/ARM-software/nomali-model. This library
implements the register interface of the Mali T6xx/T7xx series GPUs,
but doesn't do any rendering. It can be used to hide the effects of
software rendering.