This allows the Vulkan runner to execute in environments which do
not support geometry shaders, most notably MoltenVK. In particular,
that enables SM<4 shaders to run in such environments
The used UAV formats are explicitly added in the [require] section of
every test that uses them.
Some of these tests were failing on Intel UHD graphics 770 because of
missing support for additional UAV load types, explicitly requiring
these formats allows these tests to be skipped.
The current default is r32g32b32a32 but it requires special support
which is not available on all GPUs, so it is not a very convenient
default.
Instead of changing the default making it different from RTV resoures,
the format is required to always be explicit for UAVs.
The exceptions are counter_buffer and buffers with "stride", which don't
require a format because it is already implied.
If in the same shader_test file we have both a [buffer uav n] and a
[uav n] with the same slot "n", we want the last one to override the
first one instead of passing both resources to the backends.
Same for [buffer srv n] and [texture n] after we introduce SRV buffers.
If the runners require multiple calls to run_shader_tests() for
different shader model ranges, these are moved inside the sole runner
call.
For the same reason, the trace() messages are also moved inside the
runner calls.
The location of dxcompiler should be set during configuration with
'DXCOMPILER_LIBS=-L/path/to/dxcompiler', and then at runtime with
LD_LIBRARY_PATH, WINEPATH or PATH as applicable.
A new 'fail(sm<6)' decoration is needed on many shader declarations
because dxcompiler succeeds on many shaders which fail with fxc. The
opposite case is less common and is flagged with 'fail(sm>=6)'. A few
tests cause dxcompiler to crash or hang, so these are avoided using
[require], which now skips tests until reset instead of exiting. Also,
'todo(sm<6)' and 'todo(sm>=6)' are used to separate checking of results.
